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

java.lang.Object
  extended by org.datanucleus.store.rdbms.sql.method.AbstractSQLMethod
      extended by 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, java.util.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,
                                   java.util.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


Copyright © 2009. All Rights Reserved.