org.datanucleus.store.rdbms.sql.method

Class CollectionSizeMethod

java.lang.Object

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

org.datanucleus.store.rdbms.sql.method.CollectionSizeMethod

All Implemented Interfaces:

SQLMethod

public class CollectionSizeMethod
extends AbstractSQLMethod

Method for evaluating {collExpr1}.size(). Returns a NumericExpression. Equates to a sub-query on the table for the collection returning the COUNT(*) of the number of elements. Something like

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

where A0 is the candidate table in the outer query, and COLLTABLE is the join table (if using join collection) or the element table (if using FK collection).

Field Summary

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

clr, exprFactory, stmt

Constructor Summary

Constructors

Constructor and Description
CollectionSizeMethod()

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

CollectionSizeMethod

public CollectionSizeMethod()

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