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, LOCALISER, stmt

Constructor Summary

CollectionIsEmptyMethod()

Method Summary

SQLExpression

getExpression(SQLExpression expr, List 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 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