Java tutorial
/******************************************************************************* * Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0 * which accompanies this distribution. * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html * and the Eclipse Distribution License is available at * http://www.eclipse.org/org/documents/edl-v10.php. * * Contributors: * Linda DeMichiel - Java Persistence 2.1 * Linda DeMichiel - Java Persistence 2.0 * ******************************************************************************/ package javax.persistence.criteria; import java.util.List; import java.util.Set; /** * The <code>Subquery</code> interface defines functionality that is * specific to subqueries. * * A subquery has an expression as its selection item. * * @param <T> the type of the selection item. * * @since Java Persistence 2.0 */ public interface Subquery<T> extends AbstractQuery<T>, Expression<T> { /** * Specify the item that is to be returned as the subquery * result. * Replaces the previously specified selection, if any. * @param expression expression specifying the item that * is to be returned as the subquery result * @return the modified subquery */ Subquery<T> select(Expression<T> expression); /** * Modify the subquery to restrict the result according * to the specified boolean expression. * Replaces the previously added restriction(s), if any. * This method only overrides the return type of the * corresponding <code>AbstractQuery</code> method. * @param restriction a simple or compound boolean expression * @return the modified subquery */ Subquery<T> where(Expression<Boolean> restriction); /** * Modify the subquery to restrict the result according * to the conjunction of the specified restriction predicates. * Replaces the previously added restriction(s), if any. * If no restrictions are specified, any previously added * restrictions are simply removed. * This method only overrides the return type of the * corresponding <code>AbstractQuery</code> method. * @param restrictions zero or more restriction predicates * @return the modified subquery */ Subquery<T> where(Predicate... restrictions); /** * Specify the expressions that are used to form groups over * the subquery results. * Replaces the previous specified grouping expressions, if any. * If no grouping expressions are specified, any previously * added grouping expressions are simply removed. * This method only overrides the return type of the * corresponding <code>AbstractQuery</code> method. * @param grouping zero or more grouping expressions * @return the modified subquery */ Subquery<T> groupBy(Expression<?>... grouping); /** * Specify the expressions that are used to form groups over * the subquery results. * Replaces the previous specified grouping expressions, if any. * If no grouping expressions are specified, any previously * added grouping expressions are simply removed. * This method only overrides the return type of the * corresponding <code>AbstractQuery</code> method. * @param grouping list of zero or more grouping expressions * @return the modified subquery */ Subquery<T> groupBy(List<Expression<?>> grouping); /** * Specify a restriction over the groups of the subquery. * Replaces the previous having restriction(s), if any. * This method only overrides the return type of the * corresponding <code>AbstractQuery</code> method. * @param restriction a simple or compound boolean expression * @return the modified subquery */ Subquery<T> having(Expression<Boolean> restriction); /** * Specify restrictions over the groups of the subquery * according the conjunction of the specified restriction * predicates. * Replaces the previously added having restriction(s), if any. * If no restrictions are specified, any previously added * restrictions are simply removed. * This method only overrides the return type of the * corresponding <code>AbstractQuery</code> method. * @param restrictions zero or more restriction predicates * @return the modified subquery */ Subquery<T> having(Predicate... restrictions); /** * Specify whether duplicate query results will be eliminated. * A true value will cause duplicates to be eliminated. * A false value will cause duplicates to be retained. * If distinct has not been specified, duplicate results must * be retained. * This method only overrides the return type of the * corresponding <code>AbstractQuery</code> method. * @param distinct boolean value specifying whether duplicate * results must be eliminated from the subquery result or * whether they must be retained * @return the modified subquery. */ Subquery<T> distinct(boolean distinct); /** * Create a subquery root correlated to a root of the * enclosing query. * @param parentRoot a root of the containing query * @return subquery root */ <Y> Root<Y> correlate(Root<Y> parentRoot); /** * Create a subquery join object correlated to a join object * of the enclosing query. * @param parentJoin join object of the containing query * @return subquery join */ <X, Y> Join<X, Y> correlate(Join<X, Y> parentJoin); /** * Create a subquery collection join object correlated to a * collection join object of the enclosing query. * @param parentCollection join object of the containing query * @return subquery join */ <X, Y> CollectionJoin<X, Y> correlate(CollectionJoin<X, Y> parentCollection); /** * Create a subquery set join object correlated to a set join * object of the enclosing query. * @param parentSet join object of the containing query * @return subquery join */ <X, Y> SetJoin<X, Y> correlate(SetJoin<X, Y> parentSet); /** * Create a subquery list join object correlated to a list join * object of the enclosing query. * @param parentList join object of the containing query * @return subquery join */ <X, Y> ListJoin<X, Y> correlate(ListJoin<X, Y> parentList); /** * Create a subquery map join object correlated to a map join * object of the enclosing query. * @param parentMap join object of the containing query * @return subquery join */ <X, K, V> MapJoin<X, K, V> correlate(MapJoin<X, K, V> parentMap); /** * Return the query of which this is a subquery. * This must be a CriteriaQuery or a Subquery. * @return the enclosing query or subquery */ AbstractQuery<?> getParent(); /** * Return the query of which this is a subquery. * This may be a CriteriaQuery, CriteriaUpdate, CriteriaDelete, * or a Subquery. * @return the enclosing query or subquery * @since Java Persistence 2.1 */ CommonAbstractCriteria getContainingQuery(); /** * Return the selection expression. * @return the item to be returned in the subquery result */ Expression<T> getSelection(); /** * Return the correlated joins of the subquery. * Returns empty set if the subquery has no correlated * joins. * Modifications to the set do not affect the query. * @return the correlated joins of the subquery */ Set<Join<?, ?>> getCorrelatedJoins(); }