Bug 187445 The joint result of script computed column is incorrect[07]
Description: 1, Each dataset including a computed column: name: index; type:integer; expression:0 2, Specify the script of datasets to: beforeOpen: index=0; onFetch: row["index"] = index; index++; 3, Join the two datasets Build number: 2.2.0.v20070516-0630 Steps to reproduce: 1, open the attached report design 2, open the joint dataset and preview Actual result: The result of column Data "Set1::index" is all 0 but no value 1.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/transform/pass/DataSetProcessUtil.java
* 
	 * @param aggrComputedColumns
	 * @throws DataException
	 */
	private void populateAggrCCs( List aggrComputedColumns )
			throws DataException
	{
		if ( aggrComputedColumns.size( ) == 0 )
			return;
		ExpressionCompiler compiler = new ExpressionCompiler( );
		compiler.setDataSetMode( true );
		try
		{
			Context cx = Context.enter( );
			List aggrInfos = new ArrayList( );
			List aggrNames = new ArrayList( );
			for ( int i = 0; i < aggrComputedColumns.size( ); i++ )
			{
				ComputedColumn cc = (ComputedColumn) aggrComputedColumns.get( i );
				List args = cc.getAggregateArgument( );
				IBaseExpression[] exprs = null;
				int offset = 0;
				if ( cc.getExpression( ) != null )
				{
					exprs = new IBaseExpression[args.size( ) + 1];
					offset = 1;
					exprs[0] = cc.getExpression( );
				}
				else
					exprs = new IBaseExpression[args.size( )];