org.datanucleus.store.rdbms.sql.method

Class CollectionIsEmptyMethod

java.lang.Object

org.datanucleus.store.rdbms.sql.method.AbstractSQLMethod

org.datanucleus.store.rdbms.sql.method.CollectionIsEmptyMethod

All Implemented Interfaces:

SQLMethod

public class CollectionIsEmptyMethod
extends AbstractSQLMethod

Method for evaluating {collExpr1}.isEmpty(). Returns a BooleanExpression, utilising the size() expression. So the SQL will be something like

 (SELECT COUNT(*) FROM COLLTABLE A0_SUB WHERE A0_SUB.OWNER_ID_OID = A0.OWNER_ID) = 0
 

Field Summary

Fields inherited from class org.datanucleus.store.rdbms.sql.method.AbstractSQLMethod

clr, exprFactory, stmt

Constructor Summary

Constructors

Constructor and Description
CollectionIsEmptyMethod()

Method Summary

Modifier and Type	Method and Description
SQLExpression	getExpression(SQLExpression expr, List<SQLExpression> args) Return the expression for this SQL function.

Methods inherited from class org.datanucleus.store.rdbms.sql.method.AbstractSQLMethod

getMappingForClass, setStatement

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CollectionIsEmptyMethod

public CollectionIsEmptyMethod()

Method Detail

getExpression

public SQLExpression getExpression(SQLExpression expr,
                                   List<SQLExpression> args)

Description copied from interface: SQLMethod

Return the expression for this SQL function.

Parameters:

expr - The expression that it is invoked on

args - Arguments passed in

Returns:

The SQL expression using the SQL function