Bug 135490 Error occurs when Preview Results of Inner Join datasets
Description: Create a sample datasource and dataset, and then create a Joint dataset. Error occurs when preview results in the data set dialog. Steps to reproduce: 1.Create a sample datasource, and a dataset with sql statement "select * from CLASSICMODELS.CUSTOMERS". 2.Create a Joint dataset, the left and right dataset is the same. 3.Preview result in the dataset dialog, error pops up continuely.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/jointdataset/JoinConditionMatcher.java
populateJoinUnit( ((IJoinCondition)joinConditions.get( i )).getLeftExpression( ), cx, i, this.left, leftRi, leftScope );
			populateJoinUnit( ((IJoinCondition)joinConditions.get( i )).getRightExpression( ), cx, i, this.right, rightRi, rightScope );
		}
		Context.exit( );
	}
	/**
	 * @param joinConditions
	 * @param cx
	 * @param i
	 */
	private void populateJoinUnit( IScriptExpression expr, Context cx, int i, JoinConditionMatchUnit[] toArray, IResultIterator ri, Scriptable scope)
	{
		ColumnInfo ci;
		
		if( (ci = QueryExecutorUtil.getColInfoFromJSExpr( cx, expr.getText( ) ))!= null )
		{
			toArray[i] = new JoinConditionMatchUnit(ri, ci.getColumnName( ));
		}
		else
		{
			toArray[i] = new JoinConditionMatchUnit( expr, scope );
		}
	}
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.birt.data.engine.impl.jointdataset.IJoinConditionMatcher#match()
	 */
	public boolean match( ) throws DataException
	{