Polishing.

Added `@since` comments for new methods and classes.
General formatting and code style tweaking.
Github references for new tests added.
Fixes for integration tests with various databases:
- Not all stores support submillisecond precision for Instant.
- Count for exists query doesn't work for all databases, nor does `LEAST(COUNT(1), 1)`
- MariaDB defaults timestamp columns to the current time.
- Ordering was applied twice.
- DATETIME in SqlServer has a most peculiar preceision. We switch to DATETIME2.

Original pull request #1195
See #1192

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/JdbcAggregateOperations.java

@@ -196,6 +196,7 @@ public interface JdbcAggregateOperations {
 	 * @param entityClass the entity type must not be {@literal null}.
 	 * @return exactly one result or {@link Optional#empty()} if no match found.
 	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if more than one match found.
+	 * @since 3.0
 	 */
 	<T> Optional<T> selectOne(Query query, Class<T> entityClass);
 
@@ -204,11 +205,11 @@ public interface JdbcAggregateOperations {
 	 *
 	 * @param query must not be {@literal null}.
 	 * @param entityClass the entity type must not be {@literal null}.
-	 * @param sort the sorting that should be used on the result.
 	 * @return a non-null sorted list with all the matching results.
 	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if more than one match found.
+	 * @since 3.0
 	 */
-	<T> Iterable<T> select(Query query, Class<T> entityClass, Sort sort);
+	<T> Iterable<T> select(Query query, Class<T> entityClass);
 
 	/**
 	 * Determine whether there are aggregates that match the {@link Query}
@@ -216,6 +217,7 @@ public interface JdbcAggregateOperations {
 	 * @param query must not be {@literal null}.
 	 * @param entityClass the entity type must not be {@literal null}.
 	 * @return {@literal true} if the object exists.
+	 * @since 3.0
 	 */
 	<T> boolean exists(Query query, Class<T> entityClass);
 
@@ -225,6 +227,7 @@ public interface JdbcAggregateOperations {
 	 * @param query must not be {@literal null}.
 	 * @param entityClass the entity type must not be {@literal null}.
 	 * @return the number of instances stored in the database. Guaranteed to be not {@code null}.
+	 * @since 3.0
 	 */
 	<T> long count(Query query, Class<T> entityClass);
 
@@ -236,6 +239,7 @@ public interface JdbcAggregateOperations {
 	 * @param entityClass the entity type must not be {@literal null}.
 	 * @param pageable can be null.
 	 * @return a {@link Page} of entities matching the given {@link Example}.
+	 * @since 3.0
 	 */
 	<T> Page<T> select(Query query, Class<T> entityClass, Pageable pageable);
 }

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/JdbcAggregateTemplate.java

@@ -74,7 +74,6 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 
 	private final DataAccessStrategy accessStrategy;
 	private final AggregateChangeExecutor executor;
-
 	private final JdbcConverter converter;
 
 	private EntityCallbacks entityCallbacks = EntityCallbacks.create();
@@ -248,7 +247,7 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 	}
 
 	@Override
-	public <T> Iterable<T> select(Query query, Class<T> entityClass, Sort sort) {
+	public <T> Iterable<T> select(Query query, Class<T> entityClass) {
 		return accessStrategy.select(query, entityClass);
 	}
 
@@ -264,16 +263,13 @@ public class JdbcAggregateTemplate implements JdbcAggregateOperations {
 
 	@Override
 	public <T> Page<T> select(Query query, Class<T> entityClass, Pageable pageable) {
+
 		Iterable<T> items = triggerAfterConvert(accessStrategy.select(query, entityClass, pageable));
 		List<T> content = StreamSupport.stream(items.spliterator(), false).collect(Collectors.toList());
 
 		return PageableExecutionUtils.getPage(content, pageable, () -> accessStrategy.count(query, entityClass));
 	}
 
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.jdbc.core.JdbcAggregateOperations#findAll(java.lang.Class)
-	 */
 	@Override
 	public <T> Iterable<T> findAll(Class<T> domainType) {
 

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/CascadingDataAccessStrategy.java

@@ -15,6 +15,8 @@
  */
 package org.springframework.data.jdbc.core.convert;
 
+import static java.lang.Boolean.*;
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
@@ -29,10 +31,8 @@ import org.springframework.data.relational.core.mapping.RelationalPersistentProp
 import org.springframework.data.relational.core.query.Query;
 import org.springframework.data.relational.core.sql.LockMode;
 
-import static java.lang.Boolean.*;
-
 /**
- * Delegates each methods to the {@link DataAccessStrategy}s passed to the constructor in turn until the first that does
+ * Delegates each method to the {@link DataAccessStrategy}s passed to the constructor in turn until the first that does
  * not throw an exception.
  *
  * @author Jens Schauder

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/DataAccessStrategy.java

@@ -114,8 +114,8 @@ public interface DataAccessStrategy extends RelationResolver {
 	 * @param previousVersion The previous version assigned to the instance being saved.
 	 * @param <T> the type of the instance to save.
 	 * @return whether the update actually updated a row.
-	 * @throws OptimisticLockingFailureException if the update fails to update at least one row assuming the
-	 *           optimistic locking version check failed.
+	 * @throws OptimisticLockingFailureException if the update fails to update at least one row assuming the optimistic
+	 *           locking version check failed.
 	 * @since 2.0
 	 */
 	<T> boolean updateWithVersion(T instance, Class<T> domainType, Number previousVersion);
@@ -155,8 +155,8 @@ public interface DataAccessStrategy extends RelationResolver {
 	 * @param domainType the type of entity to be deleted. Implicitly determines the table to operate on. Must not be
 	 *          {@code null}.
 	 * @param previousVersion The previous version assigned to the instance being saved.
-	 * @throws OptimisticLockingFailureException if the update fails to update at least one row assuming the
-	 *           optimistic locking version check failed.
+	 * @throws OptimisticLockingFailureException if the update fails to update at least one row assuming the optimistic
+	 *           locking version check failed.
 	 * @since 2.0
 	 */
 	<T> void deleteWithVersion(Object id, Class<T> domainType, Number previousVersion);
@@ -292,6 +292,7 @@ public interface DataAccessStrategy extends RelationResolver {
 	 * @param probeType the type of entities. Must not be {@code null}.
 	 * @return exactly one result or {@link Optional#empty()} if no match found.
 	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if more than one match found.
+	 * @since 3.0
 	 */
 	<T> Optional<T> selectOne(Query query, Class<T> probeType);
 
@@ -302,6 +303,7 @@ public interface DataAccessStrategy extends RelationResolver {
 	 * @param probeType the type of entities. Must not be {@code null}.
 	 * @return a non-null list with all the matching results.
 	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if more than one match found.
+	 * @since 3.0
 	 */
 	<T> Iterable<T> select(Query query, Class<T> probeType);
 
@@ -314,6 +316,7 @@ public interface DataAccessStrategy extends RelationResolver {
 	 * @param pageable the pagination that should be applied. Must not be {@literal null}.
 	 * @return a non-null list with all the matching results.
 	 * @throws org.springframework.dao.IncorrectResultSizeDataAccessException if more than one match found.
+	 * @since 3.0
 	 */
 	<T> Iterable<T> select(Query query, Class<T> probeType, Pageable pageable);
 
@@ -323,6 +326,7 @@ public interface DataAccessStrategy extends RelationResolver {
 	 * @param query must not be {@literal null}.
 	 * @param probeType the type of entities. Must not be {@code null}.
 	 * @return {@literal true} if the object exists.
+	 * @since 3.0
 	 */
 	<T> boolean exists(Query query, Class<T> probeType);
 
@@ -332,6 +336,7 @@ public interface DataAccessStrategy extends RelationResolver {
 	 * @param probeType the probe type for which to count the elements. Must not be {@code null}.
 	 * @param query the query which elements have to match.
 	 * @return the count. Guaranteed to be not {@code null}.
+	 * @since 3.0
 	 */
 	<T> long count(Query query, Class<T> probeType);
 }

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/DefaultDataAccessStrategy.java

@@ -20,9 +20,7 @@ import static org.springframework.data.jdbc.core.convert.SqlGenerator.*;
 import java.sql.ResultSet;
 import java.util.Collections;
 import java.util.List;
-import java.util.Map;
 import java.util.Optional;
-import java.util.function.Predicate;
 
 import org.springframework.dao.EmptyResultDataAccessException;
 import org.springframework.dao.OptimisticLockingFailureException;
@@ -262,27 +260,24 @@ public class DefaultDataAccessStrategy implements DataAccessStrategy {
 	}
 
 	@Override
-	@SuppressWarnings("unchecked")
 	public <T> T findById(Object id, Class<T> domainType) {
 
 		String findOneSql = sql(domainType).getFindOne();
 		SqlIdentifierParameterSource parameter = sqlParametersFactory.forQueryById(id, domainType, ID_SQL_PARAMETER);
 
 		try {
-			return operations.queryForObject(findOneSql, parameter, (RowMapper<T>) getEntityRowMapper(domainType));
+			return operations.queryForObject(findOneSql, parameter, getEntityRowMapper(domainType));
 		} catch (EmptyResultDataAccessException e) {
 			return null;
 		}
 	}
 
 	@Override
-	@SuppressWarnings("unchecked")
 	public <T> Iterable<T> findAll(Class<T> domainType) {
-		return operations.query(sql(domainType).getFindAll(), (RowMapper<T>) getEntityRowMapper(domainType));
+		return operations.query(sql(domainType).getFindAll(), getEntityRowMapper(domainType));
 	}
 
 	@Override
-	@SuppressWarnings("unchecked")
 	public <T> Iterable<T> findAllById(Iterable<?> ids, Class<T> domainType) {
 
 		if (!ids.iterator().hasNext()) {
@@ -293,7 +288,7 @@ public class DefaultDataAccessStrategy implements DataAccessStrategy {
 
 		String findAllInListSql = sql(domainType).getFindAllInList();
 
-		return operations.query(findAllInListSql, parameterSource, (RowMapper<T>) getEntityRowMapper(domainType));
+		return operations.query(findAllInListSql, parameterSource, getEntityRowMapper(domainType));
 	}
 
 	@Override
@@ -330,73 +325,74 @@ public class DefaultDataAccessStrategy implements DataAccessStrategy {
 	}
 
 	@Override
-	@SuppressWarnings("unchecked")
 	public <T> Iterable<T> findAll(Class<T> domainType, Sort sort) {
-		return operations.query(sql(domainType).getFindAll(sort), (RowMapper<T>) getEntityRowMapper(domainType));
+		return operations.query(sql(domainType).getFindAll(sort), getEntityRowMapper(domainType));
 	}
 
 	@Override
-	@SuppressWarnings("unchecked")
 	public <T> Iterable<T> findAll(Class<T> domainType, Pageable pageable) {
-		return operations.query(sql(domainType).getFindAll(pageable), (RowMapper<T>) getEntityRowMapper(domainType));
+		return operations.query(sql(domainType).getFindAll(pageable), getEntityRowMapper(domainType));
 	}
 
 	@Override
 	public <T> Optional<T> selectOne(Query query, Class<T> probeType) {
+
 		MapSqlParameterSource parameterSource = new MapSqlParameterSource();
 		String sqlQuery = sql(probeType).selectByQuery(query, parameterSource);
 
-		T foundObject;
 		try {
-			foundObject = operations.queryForObject(sqlQuery, parameterSource, (RowMapper<T>) getEntityRowMapper(probeType));
+			return Optional.ofNullable(
+					operations.queryForObject(sqlQuery, parameterSource, getEntityRowMapper(probeType)));
 		} catch (EmptyResultDataAccessException e) {
-			foundObject = null;
+			return Optional.empty();
 		}
-
-		return Optional.ofNullable(foundObject);
 	}
 
 	@Override
 	public <T> Iterable<T> select(Query query, Class<T> probeType) {
+
 		MapSqlParameterSource parameterSource = new MapSqlParameterSource();
 		String sqlQuery = sql(probeType).selectByQuery(query, parameterSource);
 
-		return operations.query(sqlQuery, parameterSource, (RowMapper<T>) getEntityRowMapper(probeType));
+		return operations.query(sqlQuery, parameterSource, getEntityRowMapper(probeType));
 	}
 
 	@Override
 	public <T> Iterable<T> select(Query query, Class<T> probeType, Pageable pageable) {
+
 		MapSqlParameterSource parameterSource = new MapSqlParameterSource();
 		String sqlQuery = sql(probeType).selectByQuery(query, parameterSource, pageable);
 
-		return operations.query(sqlQuery, parameterSource, (RowMapper<T>) getEntityRowMapper(probeType));
+		return operations.query(sqlQuery, parameterSource, getEntityRowMapper(probeType));
 	}
 
 	@Override
 	public <T> boolean exists(Query query, Class<T> probeType) {
-		MapSqlParameterSource parameterSource = new MapSqlParameterSource();
 
+		MapSqlParameterSource parameterSource = new MapSqlParameterSource();
 		String sqlQuery = sql(probeType).existsByQuery(query, parameterSource);
 
 		Boolean result = operations.queryForObject(sqlQuery, parameterSource, Boolean.class);
-		Assert.notNull(result, "The result of an exists query must not be null");
+
+		Assert.state(result != null, "The result of an exists query must not be null");
 
 		return result;
 	}
 
 	@Override
 	public <T> long count(Query query, Class<T> probeType) {
+
 		MapSqlParameterSource parameterSource = new MapSqlParameterSource();
 		String sqlQuery = sql(probeType).countByQuery(query, parameterSource);
 
 		Long result = operations.queryForObject(sqlQuery, parameterSource, Long.class);
 
-		Assert.notNull(result, "The result of a count query must not be null.");
+		Assert.state(result != null, "The result of a count query must not be null.");
 
 		return result;
 	}
 
-	private EntityRowMapper<?> getEntityRowMapper(Class<?> domainType) {
+	private <T> EntityRowMapper<T> getEntityRowMapper(Class<T> domainType) {
 		return new EntityRowMapper<>(getRequiredPersistentEntity(domainType), converter);
 	}
 

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/DelegatingDataAccessStrategy.java

@@ -16,6 +16,7 @@
 package org.springframework.data.jdbc.core.convert;
 
 import java.util.List;
+import java.util.Optional;
 
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
@@ -26,8 +27,6 @@ import org.springframework.data.relational.core.query.Query;
 import org.springframework.data.relational.core.sql.LockMode;
 import org.springframework.util.Assert;
 
-import java.util.Optional;
-
 /**
  * Delegates all method calls to an instance set after construction. This is useful for {@link DataAccessStrategy}s with
  * cyclic dependencies.

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/QueryMapper.java

@@ -55,7 +55,7 @@ import org.springframework.util.ClassUtils;
  *
  * @author Mark Paluch
  * @author Jens Schauder
- * @since 2.0
+ * @since 3.0
  */
 public class QueryMapper {
 
@@ -85,7 +85,7 @@ public class QueryMapper {
 	 *
 	 * @param sort must not be {@literal null}.
 	 * @param entity related {@link RelationalPersistentEntity}, can be {@literal null}.
-	 * @return
+	 * @return a List of {@link OrderByField} objects guaranteed to be not {@literal null}.
 	 */
 	public List<OrderByField> getMappedSort(Table table, Sort sort, @Nullable RelationalPersistentEntity<?> entity) {
 
@@ -116,9 +116,8 @@ public class QueryMapper {
 			return expression;
 		}
 
-		if (expression instanceof Column) {
+		if (expression instanceof Column column) {
 
-			Column column = (Column) expression;
 			Field field = createPropertyField(entity, column.getName());
 			TableLike table = column.getTable();
 
@@ -128,9 +127,7 @@ public class QueryMapper {
 			return column instanceof Aliased ? columnFromTable.as(((Aliased) column).getAlias()) : columnFromTable;
 		}
 
-		if (expression instanceof SimpleFunction) {
-
-			SimpleFunction function = (SimpleFunction) expression;
+		if (expression instanceof SimpleFunction function) {
 
 			List<Expression> arguments = function.getExpressions();
 			List<Expression> mappedArguments = new ArrayList<>(arguments.size());
@@ -280,9 +277,7 @@ public class QueryMapper {
 		Object mappedValue;
 		SQLType sqlType;
 
-		if (criteria.getValue() instanceof JdbcValue) {
-
-			JdbcValue settableValue = (JdbcValue) criteria.getValue();
+		if (criteria.getValue() instanceof JdbcValue settableValue) {
 
 			mappedValue = convertValue(settableValue.getValue(), propertyField.getTypeHint());
 			sqlType = getTypeHint(mappedValue, actualType.getType(), settableValue);
@@ -554,40 +549,39 @@ public class QueryMapper {
 		String refName = column.getName().getReference();
 
 		switch (comparator) {
-			case EQ: {
+			case EQ -> {
 				Expression expression = bind(mappedValue, sqlType, parameterSource, refName, ignoreCase);
 				return Conditions.isEqual(columnExpression, expression);
 			}
-			case NEQ: {
+			case NEQ -> {
 				Expression expression = bind(mappedValue, sqlType, parameterSource, refName, ignoreCase);
 				return Conditions.isEqual(columnExpression, expression).not();
 			}
-			case LT: {
+			case LT -> {
 				Expression expression = bind(mappedValue, sqlType, parameterSource, refName);
 				return column.isLess(expression);
 			}
-			case LTE: {
+			case LTE -> {
 				Expression expression = bind(mappedValue, sqlType, parameterSource, refName);
 				return column.isLessOrEqualTo(expression);
 			}
-			case GT: {
+			case GT -> {
 				Expression expression = bind(mappedValue, sqlType, parameterSource, refName);
 				return column.isGreater(expression);
 			}
-			case GTE: {
+			case GTE -> {
 				Expression expression = bind(mappedValue, sqlType, parameterSource, refName);
 				return column.isGreaterOrEqualTo(expression);
 			}
-			case LIKE: {
+			case LIKE -> {
 				Expression expression = bind(mappedValue, sqlType, parameterSource, refName, ignoreCase);
 				return Conditions.like(columnExpression, expression);
 			}
-			case NOT_LIKE: {
+			case NOT_LIKE -> {
 				Expression expression = bind(mappedValue, sqlType, parameterSource, refName, ignoreCase);
 				return Conditions.notLike(columnExpression, expression);
 			}
-			default:
-				throw new UnsupportedOperationException("Comparator " + comparator + " not supported");
+			default -> throw new UnsupportedOperationException("Comparator " + comparator + " not supported");
 		}
 	}
 
@@ -677,7 +671,7 @@ public class QueryMapper {
 		/**
 		 * Returns the key to be used in the mapped document eventually.
 		 *
-		 * @return
+		 * @return  the key to be used in the mapped document eventually.
 		 */
 		public SqlIdentifier getMappedColumnName() {
 			return this.name;
@@ -774,9 +768,6 @@ public class QueryMapper {
 
 		/**
 		 * Returns the {@link PersistentPropertyPath} for the given {@code pathExpression}.
-		 *
-		 * @param pathExpression
-		 * @return
 		 */
 		@Nullable
 		private PersistentPropertyPath<RelationalPersistentProperty> getPath(String pathExpression) {

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/core/convert/SqlGenerator.java

@@ -88,6 +88,7 @@ class SqlGenerator {
 	private final Lazy<String> deleteByIdAndVersionSql = Lazy.of(this::createDeleteByIdAndVersionSql);
 	private final Lazy<String> deleteByListSql = Lazy.of(this::createDeleteByListSql);
 	private final QueryMapper queryMapper;
+	private final Dialect dialect;
 
 	/**
 	 * Create a new {@link SqlGenerator} given {@link RelationalMappingContext} and {@link RelationalPersistentEntity}.
@@ -107,6 +108,7 @@ class SqlGenerator {
 		this.sqlRenderer = SqlRenderer.create(renderContext);
 		this.columns = new Columns(entity, mappingContext, converter);
 		this.queryMapper = new QueryMapper(dialect, converter);
+		this.dialect = dialect;
 	}
 
 	/**
@@ -668,15 +670,6 @@ class SqlGenerator {
 		return render(delete);
 	}
 
-	private String createDeleteByIdInAndVersionSql() {
-
-		Delete delete = createBaseDeleteByIdIn(getTable()) //
-				.and(getVersionColumn().isEqualTo(SQL.bindMarker(":" + renderReference(VERSION_SQL_PARAMETER)))) //
-				.build();
-
-		return render(delete);
-	}
-
 	private DeleteBuilder.DeleteWhereAndOr createBaseDeleteById(Table table) {
 
 		return Delete.builder().from(table)
@@ -827,8 +820,7 @@ class SqlGenerator {
 	 */
 	public String existsByQuery(Query query, MapSqlParameterSource parameterSource) {
 
-		Expression idColumn = getIdColumn();
-		SelectBuilder.SelectJoin baseSelect = getSelectCountWithExpression(idColumn);
+		SelectBuilder.SelectJoin baseSelect = getExistsSelect();
 
 		Select select = applyQueryOnSelect(query, parameterSource, (SelectBuilder.SelectWhere) baseSelect) //
 				.build();
@@ -855,6 +847,36 @@ class SqlGenerator {
 		return render(select);
 	}
 
+	/**
+	 * Generates a {@link org.springframework.data.relational.core.sql.SelectBuilder.SelectJoin} with a
+	 * <code>COUNT(...)</code> where the <code>countExpressions</code> are the parameters of the count.
+	 *
+	 * @return a non-null {@link org.springframework.data.relational.core.sql.SelectBuilder.SelectJoin} that joins all the
+	 *         columns and has only a count in the projection of the select.
+	 */
+	private SelectBuilder.SelectJoin getExistsSelect() {
+
+		Table table = getTable();
+
+		SelectBuilder.SelectJoin baseSelect = StatementBuilder //
+				.select(dialect.getExistsFunction()) //
+				.from(table);
+
+		// add possible joins
+		for (PersistentPropertyPath<RelationalPersistentProperty> path : mappingContext
+				.findPersistentPropertyPaths(entity.getType(), p -> true)) {
+
+			PersistentPropertyPathExtension extPath = new PersistentPropertyPathExtension(mappingContext, path);
+
+			// add a join if necessary
+			Join join = getJoin(extPath);
+			if (join != null) {
+				baseSelect = baseSelect.leftOuterJoin(join.joinTable).on(join.joinColumn).equals(join.parentId);
+			}
+		}
+		return baseSelect;
+	}
+
 	/**
 	 * Generates a {@link org.springframework.data.relational.core.sql.SelectBuilder.SelectJoin} with a
 	 * <code>COUNT(...)</code> where the <code>countExpressions</code> are the parameters of the count.
@@ -869,11 +891,10 @@ class SqlGenerator {
 		Assert.state(countExpressions.length >= 1, "countExpressions must contain at least one expression");
 
 		Table table = getTable();
-		SelectBuilder.SelectFromAndJoin selectBuilder = StatementBuilder //
-				.select(Functions.count(countExpressions)) //
-				.from(table);//
 
-		SelectBuilder.SelectJoin baseSelect = selectBuilder;
+		SelectBuilder.SelectJoin baseSelect = StatementBuilder //
+				.select(Functions.count(countExpressions)) //
+				.from(table);
 
 		// add possible joins
 		for (PersistentPropertyPath<RelationalPersistentProperty> path : mappingContext

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/mybatis/MyBatisDataAccessStrategy.java

@@ -22,10 +22,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
-import java.util.stream.Collectors;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
 import org.apache.ibatis.session.SqlSession;
 import org.mybatis.spring.SqlSessionTemplate;
 import org.springframework.dao.EmptyResultDataAccessException;
@@ -352,10 +349,6 @@ public class MyBatisDataAccessStrategy implements DataAccessStrategy {
 		throw new UnsupportedOperationException("Not implemented");
 	}
 
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.data.jdbc.core.DataAccessStrategy#count(java.lang.Class)
-	 */
 	@Override
 	public long count(Class<?> domainType) {
 

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/repository/support/FetchableFluentQueryByExample.java

@@ -34,6 +34,7 @@ import org.springframework.data.relational.repository.query.RelationalExampleMap
  * {@link org.springframework.data.repository.query.FluentQuery.FetchableFluentQuery} using {@link Example}.
  *
  * @author Diego Krupitza
+ * @since 3.0
  */
 class FetchableFluentQueryByExample<S, R> extends FluentQuerySupport<S, R> {
 
@@ -47,40 +48,47 @@ class FetchableFluentQueryByExample<S, R> extends FluentQuerySupport<S, R> {
 
 	FetchableFluentQueryByExample(Example<S> example, Sort sort, Class<R> resultType, List<String> fieldsToInclude,
 			RelationalExampleMapper exampleMapper, JdbcAggregateOperations entityOperations) {
+
 		super(example, sort, resultType, fieldsToInclude);
+
 		this.exampleMapper = exampleMapper;
 		this.entityOperations = entityOperations;
 	}
 
 	@Override
 	public R oneValue() {
+
 		return this.entityOperations.selectOne(createQuery(), getExampleType())
 				.map(item -> this.getConversionFunction().apply(item)).get();
 	}
 
 	@Override
 	public R firstValue() {
+
 		return this.getConversionFunction()
-				.apply(this.entityOperations.select(createQuery(), getExampleType(), getSort()).iterator().next());
+				.apply(this.entityOperations.select(createQuery().sort(getSort()), getExampleType()).iterator().next());
 	}
 
 	@Override
 	public List<R> all() {
+
 		return StreamSupport
-				.stream(this.entityOperations.select(createQuery(), getExampleType(), getSort()).spliterator(), false)
+				.stream(this.entityOperations.select(createQuery().sort(getSort()), getExampleType()).spliterator(), false)
 				.map(item -> this.getConversionFunction().apply(item)).collect(Collectors.toList());
 	}
 
 	@Override
 	public Page<R> page(Pageable pageable) {
+
 		return this.entityOperations.select(createQuery(p -> p.with(pageable)), getExampleType(), pageable)
 				.map(item -> this.getConversionFunction().apply(item));
 	}
 
 	@Override
 	public Stream<R> stream() {
+
 		return StreamSupport
-				.stream(this.entityOperations.select(createQuery(), getExampleType(), getSort()).spliterator(), false)
+				.stream(this.entityOperations.select(createQuery().sort(getSort()), getExampleType()).spliterator(), false)
 				.map(item -> this.getConversionFunction().apply(item));
 	}
 
@@ -102,10 +110,6 @@ class FetchableFluentQueryByExample<S, R> extends FluentQuerySupport<S, R> {
 
 		Query query = exampleMapper.getMappedExample(getExample());
 
-		if (getSort().isSorted()) {
-			query = query.sort(getSort());
-		}
-
 		if (!getFieldsToInclude().isEmpty()) {
 			query = query.columns(getFieldsToInclude().toArray(new String[0]));
 		}
@@ -118,6 +122,7 @@ class FetchableFluentQueryByExample<S, R> extends FluentQuerySupport<S, R> {
 	@Override
 	protected <R> FluentQuerySupport<S, R> create(Example<S> example, Sort sort, Class<R> resultType,
 			List<String> fieldsToInclude) {
+
 		return new FetchableFluentQueryByExample<>(example, sort, resultType, fieldsToInclude, this.exampleMapper,
 				this.entityOperations);
 	}

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/repository/support/FluentQuerySupport.java

@@ -31,6 +31,7 @@ import java.util.function.Function;
  * Support class for {@link FluentQuery.FetchableFluentQuery} implementations.
  *
  * @author Diego Krupitza
+ * @since 3.0
  */
 abstract class FluentQuerySupport<S, R> implements FluentQuery.FetchableFluentQuery<R> {
 
@@ -42,6 +43,7 @@ abstract class FluentQuerySupport<S, R> implements FluentQuery.FetchableFluentQu
 	private final SpelAwareProxyProjectionFactory projectionFactory = new SpelAwareProxyProjectionFactory();
 
 	FluentQuerySupport(Example<S> example, Sort sort, Class<R> resultType, List<String> fieldsToInclude) {
+
 		this.example = example;
 		this.sort = sort;
 		this.resultType = resultType;
@@ -123,5 +125,4 @@ abstract class FluentQuerySupport<S, R> implements FluentQuery.FetchableFluentQu
 	protected Function<Object, R> getConversionFunction() {
 		return getConversionFunction(this.example.getProbeType(), getResultType());
 	}
-
 }

spring-data-jdbc/src/main/java/org/springframework/data/jdbc/repository/support/SimpleJdbcRepository.java

@@ -17,7 +17,6 @@ package org.springframework.data.jdbc.repository.support;
 
 import java.util.Optional;
 import java.util.function.Function;
-import java.util.stream.Collectors;
 
 import org.springframework.data.domain.Example;
 import org.springframework.data.domain.Page;
@@ -26,11 +25,13 @@ import org.springframework.data.domain.Sort;
 import org.springframework.data.jdbc.core.JdbcAggregateOperations;
 import org.springframework.data.jdbc.core.convert.JdbcConverter;
 import org.springframework.data.mapping.PersistentEntity;
+import org.springframework.data.relational.core.query.Query;
 import org.springframework.data.relational.repository.query.RelationalExampleMapper;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.PagingAndSortingRepository;
 import org.springframework.data.repository.query.FluentQuery;
 import org.springframework.data.repository.query.QueryByExampleExecutor;
+import org.springframework.data.support.PageableExecutionUtils;
 import org.springframework.data.util.Streamable;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.util.Assert;
@@ -141,50 +142,58 @@ public class SimpleJdbcRepository<T, ID>
 
 	@Override
 	public <S extends T> Optional<S> findOne(Example<S> example) {
-		Assert.notNull(example, "Example must not be null!");
+
+		Assert.notNull(example, "Example must not be null");
+
 		return this.entityOperations.selectOne(this.exampleMapper.getMappedExample(example), example.getProbeType());
 	}
 
 	@Override
 	public <S extends T> Iterable<S> findAll(Example<S> example) {
-		Assert.notNull(example, "Example must not be null!");
+
+		Assert.notNull(example, "Example must not be null");
 
 		return findAll(example, Sort.unsorted());
 	}
 
 	@Override
 	public <S extends T> Iterable<S> findAll(Example<S> example, Sort sort) {
-		Assert.notNull(example, "Example must not be null!");
-		Assert.notNull(sort, "Sort must not be null!");
 
-		return this.entityOperations.select(this.exampleMapper.getMappedExample(example), example.getProbeType(), sort);
+		Assert.notNull(example, "Example must not be null");
+		Assert.notNull(sort, "Sort must not be null");
+
+		return this.entityOperations.select(this.exampleMapper.getMappedExample(example).sort(sort),
+				example.getProbeType());
 	}
 
 	@Override
 	public <S extends T> Page<S> findAll(Example<S> example, Pageable pageable) {
-		Assert.notNull(example, "Example must not be null!");
+
+		Assert.notNull(example, "Example must not be null");
 
 		return this.entityOperations.select(this.exampleMapper.getMappedExample(example), example.getProbeType(), pageable);
 	}
 
 	@Override
 	public <S extends T> long count(Example<S> example) {
-		Assert.notNull(example, "Example must not be null!");
+
+		Assert.notNull(example, "Example must not be null");
 
 		return this.entityOperations.count(this.exampleMapper.getMappedExample(example), example.getProbeType());
 	}
 
 	@Override
 	public <S extends T> boolean exists(Example<S> example) {
-		Assert.notNull(example, "Example must not be null!");
+		Assert.notNull(example, "Example must not be null");
 
 		return this.entityOperations.exists(this.exampleMapper.getMappedExample(example), example.getProbeType());
 	}
 
 	@Override
 	public <S extends T, R> R findBy(Example<S> example, Function<FluentQuery.FetchableFluentQuery<S>, R> queryFunction) {
-		Assert.notNull(example, "Sample must not be null!");
-		Assert.notNull(queryFunction, "Query function must not be null!");
+
+		Assert.notNull(example, "Sample must not be null");
+		Assert.notNull(queryFunction, "Query function must not be null");
 
 		FluentQuery.FetchableFluentQuery<S> fluentQuery = new FetchableFluentQueryByExample<>(example,
 				example.getProbeType(), this.exampleMapper, this.entityOperations);

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/core/convert/SqlGeneratorUnitTests.java

@@ -742,10 +742,10 @@ class SqlGeneratorUnitTests {
 						SqlIdentifier.quoted("child"), SqlIdentifier.quoted("CHILD_PARENT_OF_NO_ID_CHILD"));
 	}
 
-	@Nullable
-	@Test
+	@Test // GH-1192
 	void selectByQueryValidTest() {
-		final SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class);
+
+		 SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class);
 
 		DummyEntity probe = new DummyEntity();
 		probe.name = "Diego";
@@ -762,9 +762,10 @@ class SqlGeneratorUnitTests {
 				.containsOnly(entry("x_name", probe.name));
 	}
 
-	@Test
+	@Test // GH-1192
 	void existsByQuerySimpleValidTest() {
-		final SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class);
+
+		SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class);
 
 		DummyEntity probe = new DummyEntity();
 		probe.name = "Diego";
@@ -781,9 +782,10 @@ class SqlGeneratorUnitTests {
 				.containsOnly(entry("x_name", probe.name));
 	}
 
-	@Test
+	@Test // GH-1192
 	void countByQuerySimpleValidTest() {
-		final SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class);
+
+		SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class);
 
 		DummyEntity probe = new DummyEntity();
 		probe.name = "Diego";
@@ -803,9 +805,10 @@ class SqlGeneratorUnitTests {
 				.containsOnly(entry("x_name", probe.name));
 	}
 
-	@Test
+	@Test // GH-1192
 	void selectByQueryPaginationValidTest() {
-		final SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class);
+
+		SqlGenerator sqlGenerator = createSqlGenerator(DummyEntity.class);
 
 		DummyEntity probe = new DummyEntity();
 		probe.name = "Diego";
@@ -829,6 +832,7 @@ class SqlGeneratorUnitTests {
 				.containsOnly(entry("x_name", probe.name));
 	}
 
+	@Nullable
 	private SqlIdentifier getAlias(Object maybeAliased) {
 
 		if (maybeAliased instanceof Aliased) {

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/repository/JdbcRepositoryIntegrationTests.java

@@ -31,6 +31,7 @@ import java.time.Instant;
 import java.time.LocalDateTime;
 import java.time.OffsetDateTime;
 import java.time.ZoneOffset;
+import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -567,7 +568,7 @@ public class JdbcRepositoryIntegrationTests {
 	@Test // GH-987
 	void queryBySimpleReference() {
 
-		final DummyEntity one = repository.save(createDummyEntity());
+		DummyEntity one = repository.save(createDummyEntity());
 		DummyEntity two = createDummyEntity();
 		two.ref = AggregateReference.to(one.idProp);
 		two = repository.save(two);
@@ -580,7 +581,7 @@ public class JdbcRepositoryIntegrationTests {
 	@Test // GH-987
 	void queryByAggregateReference() {
 
-		final DummyEntity one = repository.save(createDummyEntity());
+		DummyEntity one = repository.save(createDummyEntity());
 		DummyEntity two = createDummyEntity();
 		two.ref = AggregateReference.to(one.idProp);
 		two = repository.save(two);
@@ -696,59 +697,28 @@ public class JdbcRepositoryIntegrationTests {
 		assertIsEqualToWithNonNullIds(reloadedRoots.get(1), root2);
 	}
 
-	private Root createRoot(String namePrefix) {
-
-		return new Root(null, namePrefix,
-				new Intermediate(null, namePrefix + "Intermediate", new Leaf(null, namePrefix + "Leaf"), emptyList()),
-				singletonList(new Intermediate(null, namePrefix + "QualifiedIntermediate", null,
-						singletonList(new Leaf(null, namePrefix + "QualifiedLeaf")))));
-	}
-
-	private void assertIsEqualToWithNonNullIds(Root reloadedRoot1, Root root1) {
-
-		assertThat(reloadedRoot1.id).isNotNull();
-		assertThat(reloadedRoot1.name).isEqualTo(root1.name);
-		assertThat(reloadedRoot1.intermediate.id).isNotNull();
-		assertThat(reloadedRoot1.intermediate.name).isEqualTo(root1.intermediate.name);
-		assertThat(reloadedRoot1.intermediates.get(0).id).isNotNull();
-		assertThat(reloadedRoot1.intermediates.get(0).name).isEqualTo(root1.intermediates.get(0).name);
-		assertThat(reloadedRoot1.intermediate.leaf.id).isNotNull();
-		assertThat(reloadedRoot1.intermediate.leaf.name).isEqualTo(root1.intermediate.leaf.name);
-		assertThat(reloadedRoot1.intermediates.get(0).leaves.get(0).id).isNotNull();
-		assertThat(reloadedRoot1.intermediates.get(0).leaves.get(0).name)
-				.isEqualTo(root1.intermediates.get(0).leaves.get(0).name);
-	}
-
-	@Test
+	@Test // GH-1192
 	void findOneByExampleShouldGetOne() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
 		dummyEntity1.setFlag(true);
-
 		repository.save(dummyEntity1);
 
 		DummyEntity dummyEntity2 = createDummyEntity();
 		dummyEntity2.setName("Diego");
-
 		repository.save(dummyEntity2);
 
 		Example<DummyEntity> diegoExample = Example.of(new DummyEntity("Diego"));
-
 		Optional<DummyEntity> foundExampleDiego = repository.findOne(diegoExample);
 
-		assertThat(foundExampleDiego).isPresent();
-		assertThat(foundExampleDiego.get()).isNotNull();
 		assertThat(foundExampleDiego.get().getName()).isEqualTo("Diego");
 	}
 
-	@Test
+	@Test // GH-1192
 	void findOneByExampleMultipleMatchShouldGetOne() {
 
-		DummyEntity dummyEntity1 = createDummyEntity();
-		repository.save(dummyEntity1);
-
-		DummyEntity dummyEntity2 = createDummyEntity();
-		repository.save(dummyEntity2);
+		repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		Example<DummyEntity> example = Example.of(createDummyEntity());
 
@@ -756,12 +726,11 @@ public class JdbcRepositoryIntegrationTests {
 				.hasMessageContaining("expected 1, actual 2");
 	}
 
-	@Test
+	@Test // GH-1192
 	void findOneByExampleShouldGetNone() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
 		dummyEntity1.setFlag(true);
-
 		repository.save(dummyEntity1);
 
 		Example<DummyEntity> diegoExample = Example.of(new DummyEntity("NotExisting"));
@@ -771,51 +740,42 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(foundExampleDiego).isNotPresent();
 	}
 
-	@Test
+	@Test // GH-1192
 	void findAllByExampleShouldGetOne() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
 		dummyEntity1.setFlag(true);
-
 		repository.save(dummyEntity1);
 
 		DummyEntity dummyEntity2 = createDummyEntity();
 		dummyEntity2.setName("Diego");
-
 		repository.save(dummyEntity2);
 
 		Example<DummyEntity> example = Example.of(new DummyEntity("Diego"));
 
 		Iterable<DummyEntity> allFound = repository.findAll(example);
 
-		assertThat(allFound) //
-				.isNotNull() //
-				.hasSize(1) //
-				.extracting(DummyEntity::getName) //
+		assertThat(allFound).extracting(DummyEntity::getName) //
 				.containsExactly(example.getProbe().getName());
 	}
 
-	@Test
+	@Test // GH-1192
 	void findAllByExampleMultipleMatchShouldGetOne() {
 
-		DummyEntity dummyEntity1 = createDummyEntity();
-		repository.save(dummyEntity1);
-
-		DummyEntity dummyEntity2 = createDummyEntity();
-		repository.save(dummyEntity2);
+		repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		Example<DummyEntity> example = Example.of(createDummyEntity());
 
 		Iterable<DummyEntity> allFound = repository.findAll(example);
 
 		assertThat(allFound) //
-				.isNotNull() //
 				.hasSize(2) //
 				.extracting(DummyEntity::getName) //
 				.containsOnly(example.getProbe().getName());
 	}
 
-	@Test
+	@Test // GH-1192
 	void findAllByExampleShouldGetNone() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
@@ -827,12 +787,10 @@ public class JdbcRepositoryIntegrationTests {
 
 		Iterable<DummyEntity> allFound = repository.findAll(example);
 
-		assertThat(allFound) //
-				.isNotNull() //
-				.isEmpty();
+		assertThat(allFound).isEmpty();
 	}
 
-	@Test
+	@Test // GH-1192
 	void findAllByExamplePageableShouldGetOne() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
@@ -850,21 +808,15 @@ public class JdbcRepositoryIntegrationTests {
 
 		Iterable<DummyEntity> allFound = repository.findAll(example, pageRequest);
 
-		assertThat(allFound) //
-				.isNotNull() //
-				.hasSize(1) //
-				.extracting(DummyEntity::getName) //
+		assertThat(allFound).extracting(DummyEntity::getName) //
 				.containsExactly(example.getProbe().getName());
 	}
 
-	@Test
+	@Test // GH-1192
 	void findAllByExamplePageableMultipleMatchShouldGetOne() {
 
-		DummyEntity dummyEntity1 = createDummyEntity();
-		repository.save(dummyEntity1);
-
-		DummyEntity dummyEntity2 = createDummyEntity();
-		repository.save(dummyEntity2);
+		repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		Example<DummyEntity> example = Example.of(createDummyEntity());
 		Pageable pageRequest = PageRequest.of(0, 10);
@@ -872,13 +824,12 @@ public class JdbcRepositoryIntegrationTests {
 		Iterable<DummyEntity> allFound = repository.findAll(example, pageRequest);
 
 		assertThat(allFound) //
-				.isNotNull() //
 				.hasSize(2) //
 				.extracting(DummyEntity::getName) //
 				.containsOnly(example.getProbe().getName());
 	}
 
-	@Test
+	@Test // GH-1192
 	void findAllByExamplePageableShouldGetNone() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
@@ -891,19 +842,14 @@ public class JdbcRepositoryIntegrationTests {
 
 		Iterable<DummyEntity> allFound = repository.findAll(example, pageRequest);
 
-		assertThat(allFound) //
-				.isNotNull() //
-				.isEmpty();
+		assertThat(allFound).isEmpty();
 	}
 
-	@Test
+	@Test // GH-1192
 	void findAllByExamplePageableOutsidePageShouldGetNone() {
 
-		DummyEntity dummyEntity1 = createDummyEntity();
-		repository.save(dummyEntity1);
-
-		DummyEntity dummyEntity2 = createDummyEntity();
-		repository.save(dummyEntity2);
+		repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		Example<DummyEntity> example = Example.of(createDummyEntity());
 		Pageable pageRequest = PageRequest.of(10, 10);
@@ -915,7 +861,7 @@ public class JdbcRepositoryIntegrationTests {
 				.isEmpty();
 	}
 
-	@ParameterizedTest
+	@ParameterizedTest // GH-1192
 	@MethodSource("findAllByExamplePageableSource")
 	void findAllByExamplePageable(Pageable pageRequest, int size, int totalPages, List<String> notContains) {
 
@@ -964,17 +910,15 @@ public class JdbcRepositoryIntegrationTests {
 		);
 	}
 
-	@Test
+	@Test // GH-1192
 	void existsByExampleShouldGetOne() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
 		dummyEntity1.setFlag(true);
-
 		repository.save(dummyEntity1);
 
 		DummyEntity dummyEntity2 = createDummyEntity();
 		dummyEntity2.setName("Diego");
-
 		repository.save(dummyEntity2);
 
 		Example<DummyEntity> example = Example.of(new DummyEntity("Diego"));
@@ -984,7 +928,7 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(exists).isTrue();
 	}
 
-	@Test
+	@Test // GH-1192
 	void existsByExampleMultipleMatchShouldGetOne() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
@@ -999,7 +943,7 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(exists).isTrue();
 	}
 
-	@Test
+	@Test // GH-1192
 	void existsByExampleShouldGetNone() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
@@ -1014,17 +958,17 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(exists).isFalse();
 	}
 
-	@Test
+	@Test // GH-1192
 	void existsByExampleComplex() {
 
-		final Instant pointInTime = Instant.now().minusSeconds(10000);
+		Instant pointInTime = Instant.now().truncatedTo(ChronoUnit.MILLIS).minusSeconds(10000);
 
-		final DummyEntity one = repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		DummyEntity two = createDummyEntity();
 		two.setName("Diego");
 		two.setPointInTime(pointInTime);
-		two = repository.save(two);
+		repository.save(two);
 
 		DummyEntity exampleEntitiy = createDummyEntity();
 		exampleEntitiy.setName("Diego");
@@ -1036,7 +980,7 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(exists).isTrue();
 	}
 
-	@Test
+	@Test // GH-1192
 	void countByExampleShouldGetOne() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
@@ -1056,7 +1000,7 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(count).isOne();
 	}
 
-	@Test
+	@Test // GH-1192
 	void countByExampleMultipleMatchShouldGetOne() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
@@ -1071,7 +1015,7 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(count).isEqualTo(2);
 	}
 
-	@Test
+	@Test // GH-1192
 	void countByExampleShouldGetNone() {
 
 		DummyEntity dummyEntity1 = createDummyEntity();
@@ -1086,17 +1030,16 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(count).isNotNull().isZero();
 	}
 
-	@Test
+	@Test // GH-1192
 	void countByExampleComplex() {
 
-		final Instant pointInTime = Instant.now().minusSeconds(10000);
-
-		final DummyEntity one = repository.save(createDummyEntity());
+		Instant pointInTime = Instant.now().minusSeconds(10000).truncatedTo(ChronoUnit.MILLIS);
+		repository.save(createDummyEntity());
 
 		DummyEntity two = createDummyEntity();
 		two.setName("Diego");
 		two.setPointInTime(pointInTime);
-		two = repository.save(two);
+		repository.save(two);
 
 		DummyEntity exampleEntitiy = createDummyEntity();
 		exampleEntitiy.setName("Diego");
@@ -1108,11 +1051,11 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(count).isOne();
 	}
 
-	@Test
+	@Test // GH-1192
 	void fetchByExampleFluentAllSimple() {
-		String searchName = "Diego";
 
-		Instant now = Instant.now();
+		String searchName = "Diego";
+		Instant now = Instant.now().truncatedTo(ChronoUnit.MILLIS);
 
 		final DummyEntity one = repository.save(createDummyEntity());
 
@@ -1121,11 +1064,17 @@ public class JdbcRepositoryIntegrationTests {
 		two.setName(searchName);
 		two.setPointInTime(now.minusSeconds(10000));
 		two = repository.save(two);
+		// certain databases consider it a great idea to assign default values to timestamp fields.
+		// I'm looking at you MariaDb.
+		two = repository.findById(two.idProp).orElseThrow();
 
 		DummyEntity third = createDummyEntity();
 		third.setName(searchName);
 		third.setPointInTime(now.minusSeconds(200000));
 		third = repository.save(third);
+		// certain databases consider it a great idea to assign default values to timestamp fields.
+		// I'm looking at you MariaDb.
+		third = repository.findById(third.idProp).orElseThrow();
 
 		DummyEntity exampleEntitiy = createDummyEntity();
 		exampleEntitiy.setName(searchName);
@@ -1133,28 +1082,27 @@ public class JdbcRepositoryIntegrationTests {
 		Example<DummyEntity> example = Example.of(exampleEntitiy);
 
 		List<DummyEntity> matches = repository.findBy(example, p -> p.sortBy(Sort.by("pointInTime").descending()).all());
-		assertThat(matches).hasSize(2).contains(two, third);
-		assertThat(matches.get(0)).isEqualTo(two);
+		assertThat(matches).containsExactly(two, third);
 	}
 
-	@Test
+	@Test // GH-1192
 	void fetchByExampleFluentCountSimple() {
-		String searchName = "Diego";
 
+		String searchName = "Diego";
 		Instant now = Instant.now();
 
-		final DummyEntity one = repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		DummyEntity two = createDummyEntity();
 
 		two.setName(searchName);
 		two.setPointInTime(now.minusSeconds(10000));
-		two = repository.save(two);
+		repository.save(two);
 
 		DummyEntity third = createDummyEntity();
 		third.setName(searchName);
 		third.setPointInTime(now.minusSeconds(200000));
-		third = repository.save(third);
+		repository.save(third);
 
 		DummyEntity exampleEntitiy = createDummyEntity();
 		exampleEntitiy.setName(searchName);
@@ -1165,53 +1113,56 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(matches).isEqualTo(2);
 	}
 
-	@Test
+	@Test // GH-1192
 	void fetchByExampleFluentOnlyInstantFirstSimple() {
-		String searchName = "Diego";
 
-		Instant now = Instant.now();
+		String searchName = "Diego";
+		Instant now = Instant.now().truncatedTo(ChronoUnit.MILLIS);
 
-		final DummyEntity one = repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		DummyEntity two = createDummyEntity();
 
 		two.setName(searchName);
 		two.setPointInTime(now.minusSeconds(10000));
 		two = repository.save(two);
+		// certain databases consider it a great idea to assign default values to timestamp fields.
+		// I'm looking at you MariaDb.
+		two = repository.findById(two.idProp).orElseThrow();
 
 		DummyEntity third = createDummyEntity();
 		third.setName(searchName);
 		third.setPointInTime(now.minusSeconds(200000));
-		third = repository.save(third);
+		repository.save(third);
 
-		DummyEntity exampleEntitiy = createDummyEntity();
-		exampleEntitiy.setName(searchName);
+		DummyEntity exampleEntity = createDummyEntity();
+		exampleEntity.setName(searchName);
 
-		Example<DummyEntity> example = Example.of(exampleEntitiy);
+		Example<DummyEntity> example = Example.of(exampleEntity);
 
 		Optional<DummyEntity> matches = repository.findBy(example,
 				p -> p.sortBy(Sort.by("pointInTime").descending()).first());
+
 		assertThat(matches).contains(two);
 	}
 
-	@Test
+	@Test // GH-1192
 	void fetchByExampleFluentOnlyInstantOneValueError() {
-		String searchName = "Diego";
 
+		String searchName = "Diego";
 		Instant now = Instant.now();
 
-		final DummyEntity one = repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		DummyEntity two = createDummyEntity();
-
 		two.setName(searchName);
 		two.setPointInTime(now.minusSeconds(10000));
-		two = repository.save(two);
+		repository.save(two);
 
 		DummyEntity third = createDummyEntity();
 		third.setName(searchName);
 		third.setPointInTime(now.minusSeconds(200000));
-		third = repository.save(third);
+		repository.save(third);
 
 		DummyEntity exampleEntitiy = createDummyEntity();
 		exampleEntitiy.setName(searchName);
@@ -1222,19 +1173,21 @@ public class JdbcRepositoryIntegrationTests {
 				.isInstanceOf(IncorrectResultSizeDataAccessException.class).hasMessageContaining("expected 1, actual 2");
 	}
 
-	@Test
+	@Test // GH-1192
 	void fetchByExampleFluentOnlyInstantOneValueSimple() {
-		String searchName = "Diego";
 
-		Instant now = Instant.now();
+		String searchName = "Diego";
+		Instant now = Instant.now().truncatedTo(ChronoUnit.MILLIS);
 
-		final DummyEntity one = repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		DummyEntity two = createDummyEntity();
-
 		two.setName(searchName);
 		two.setPointInTime(now.minusSeconds(10000));
 		two = repository.save(two);
+		// certain databases consider it a great idea to assign default values to timestamp fields.
+		// I'm looking at you MariaDb.
+		two = repository.findById(two.idProp).orElseThrow();
 
 		DummyEntity exampleEntitiy = createDummyEntity();
 		exampleEntitiy.setName(searchName);
@@ -1246,30 +1199,52 @@ public class JdbcRepositoryIntegrationTests {
 		assertThat(match).contains(two);
 	}
 
-	@Test
+	@Test // GH-1192
 	void fetchByExampleFluentOnlyInstantOneValueAsSimple() {
-		String searchName = "Diego";
 
+		String searchName = "Diego";
 		Instant now = Instant.now();
 
-		final DummyEntity one = repository.save(createDummyEntity());
+		repository.save(createDummyEntity());
 
 		DummyEntity two = createDummyEntity();
-
 		two.setName(searchName);
 		two.setPointInTime(now.minusSeconds(10000));
 		two = repository.save(two);
 
-		DummyEntity exampleEntitiy = createDummyEntity();
-		exampleEntitiy.setName(searchName);
+		DummyEntity exampleEntity = createDummyEntity();
+		exampleEntity.setName(searchName);
 
-		Example<DummyEntity> example = Example.of(exampleEntitiy);
+		Example<DummyEntity> example = Example.of(exampleEntity);
 
 		Optional<DummyProjectExample> match = repository.findBy(example, p -> p.as(DummyProjectExample.class).one());
 
 		assertThat(match.get().getName()).contains(two.getName());
 	}
 
+	private Root createRoot(String namePrefix) {
+
+		return new Root(null, namePrefix,
+				new Intermediate(null, namePrefix + "Intermediate", new Leaf(null, namePrefix + "Leaf"), emptyList()),
+				singletonList(new Intermediate(null, namePrefix + "QualifiedIntermediate", null,
+						singletonList(new Leaf(null, namePrefix + "QualifiedLeaf")))));
+	}
+
+	private void assertIsEqualToWithNonNullIds(Root reloadedRoot1, Root root1) {
+
+		assertThat(reloadedRoot1.id).isNotNull();
+		assertThat(reloadedRoot1.name).isEqualTo(root1.name);
+		assertThat(reloadedRoot1.intermediate.id).isNotNull();
+		assertThat(reloadedRoot1.intermediate.name).isEqualTo(root1.intermediate.name);
+		assertThat(reloadedRoot1.intermediates.get(0).id).isNotNull();
+		assertThat(reloadedRoot1.intermediates.get(0).name).isEqualTo(root1.intermediates.get(0).name);
+		assertThat(reloadedRoot1.intermediate.leaf.id).isNotNull();
+		assertThat(reloadedRoot1.intermediate.leaf.name).isEqualTo(root1.intermediate.leaf.name);
+		assertThat(reloadedRoot1.intermediates.get(0).leaves.get(0).id).isNotNull();
+		assertThat(reloadedRoot1.intermediates.get(0).leaves.get(0).name)
+				.isEqualTo(root1.intermediates.get(0).leaves.get(0).name);
+	}
+
 	private Instant createDummyBeforeAndAfterNow() {
 
 		Instant now = Instant.now();

spring-data-jdbc/src/test/resources/org.springframework.data.jdbc.repository/JdbcRepositoryIntegrationTests-mssql.sql

@@ -7,7 +7,7 @@ CREATE TABLE dummy_entity
 (
     id_Prop          BIGINT IDENTITY PRIMARY KEY,
     NAME             VARCHAR(100),
-    POINT_IN_TIME    DATETIME,
+    POINT_IN_TIME    DATETIME2,
     OFFSET_DATE_TIME DATETIMEOFFSET,
     FLAG             BIT,
     REF              BIGINT,

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/Dialect.java

@@ -19,7 +19,10 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Set;
 
+import org.springframework.data.relational.core.sql.Functions;
 import org.springframework.data.relational.core.sql.IdentifierProcessing;
+import org.springframework.data.relational.core.sql.SQL;
+import org.springframework.data.relational.core.sql.SimpleFunction;
 import org.springframework.data.relational.core.sql.SqlIdentifier;
 import org.springframework.data.relational.core.sql.render.SelectRenderContext;
 
@@ -131,4 +134,14 @@ public interface Dialect {
 	default OrderByNullPrecedence orderByNullHandling() {
 		return OrderByNullPrecedence.SQL_STANDARD;
 	}
+
+	/**
+	 * Provide a SQL function that is suitable for implementing an exists-query.
+	 * The default is `COUNT(1)`, but for some database a `LEAST(COUNT(1), 1)` might be required, which doesn't get accepted by other databases.
+	 *
+	 * @since 3.0
+	 */
+	default SimpleFunction getExistsFunction(){
+		return Functions.count(SQL.literalOf(1));
+	}
 }

spring-data-relational/src/main/java/org/springframework/data/relational/core/dialect/PostgresDialect.java

@@ -23,10 +23,13 @@ import java.util.List;
 import java.util.Set;
 import java.util.function.Consumer;
 
+import org.springframework.data.relational.core.sql.Functions;
 import org.springframework.data.relational.core.sql.IdentifierProcessing;
 import org.springframework.data.relational.core.sql.IdentifierProcessing.LetterCasing;
 import org.springframework.data.relational.core.sql.IdentifierProcessing.Quoting;
 import org.springframework.data.relational.core.sql.LockOptions;
+import org.springframework.data.relational.core.sql.SQL;
+import org.springframework.data.relational.core.sql.SimpleFunction;
 import org.springframework.data.relational.core.sql.SqlIdentifier;
 import org.springframework.data.relational.core.sql.TableLike;
 import org.springframework.util.Assert;
@@ -193,4 +196,9 @@ public class PostgresDialect extends AbstractDialect {
 			action.accept(ClassUtils.resolveClassName(className, PostgresDialect.class.getClassLoader()));
 		}
 	}
+
+	@Override
+	public SimpleFunction getExistsFunction() {
+		return Functions.least(Functions.count(SQL.literalOf(1)), SQL.literalOf(1));
+	}
 }

spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/Functions.java

@@ -48,6 +48,11 @@ public class Functions {
 		return SimpleFunction.create("COUNT", Arrays.asList(columns));
 	}
 
+	public static SimpleFunction least(Expression... expressions) {
+
+		return SimpleFunction.create("LEAST", Arrays.asList(expressions));
+	}
+
 	/**
 	 * Creates a new {@code COUNT} function.
 	 *