org.datanucleus.store.rdbms.sql.method

Class SimpleNumericAggregateMethod

java.lang.Object

org.datanucleus.store.rdbms.sql.method.SimpleNumericAggregateMethod

All Implemented Interfaces:

SQLMethod

Direct Known Subclasses:

AvgFunction, SumFunction

public abstract class SimpleNumericAggregateMethod
extends Object
implements SQLMethod

Expression handler to invoke an SQL aggregated function.

• The expression should be null and will return an AggregateExpression

  {functionName}({argExpr})

  when processing a result clause
• If the compilation component is something else then will generate a subquery expression

Constructor Summary

Constructors

Constructor and Description
SimpleNumericAggregateMethod()

Method Summary

Modifier and Type	Method and Description
protected abstract Class	getClassForMapping()
SQLExpression	getExpression(SQLStatement stmt, SQLExpression expr, List<SQLExpression> args) Return the expression for this SQL function.
protected abstract String	getFunctionName()

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleNumericAggregateMethod

public SimpleNumericAggregateMethod()

Method Detail

getFunctionName

protected abstract String getFunctionName()

getExpression

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

Description copied from interface: SQLMethod

Return the expression for this SQL function.

Specified by:

getExpression in interface SQLMethod

Parameters:

stmt - SQLStatement that this expression is for

expr - The expression that it is invoked on

args - Arguments passed in

Returns:

The SQL expression using the SQL function

getClassForMapping

protected abstract Class getClassForMapping()