Bug 142939 Invalid interval will cause incorrect group action.
Description: Invalid interval will cause incorrect group action. Steps to reproduce: 1. Insert a list 2. Add a group, key is string type column, set interval to year, range to 3 3. Preview Expected result: Error msg about invald interval and ignore the invalid interval. Actual result: No error msg and only return one group with all datarows.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryExecutor.java
else
		{
			expr = getColumnRefExpression( expr );
		}
		return expr;
	}
	/**
	 * 
	 * @param expr
	 * @return
	 */
	private String getColumnRefExpression( String expr )
	{
		return "row[\""
				+ JavascriptEvalUtil.transformToJsConstants( expr ) + "\"]";
	}
	void setParentExecutorHelper( IExecutorHelper helper )
	{
		this.parentHelper = helper;
	}
	/**
	 * 
	 * @param cx
	 * @param dataSetFilters
	 * @param queryFilters
	 * @param temporaryComputedColumns
	 * @return
	 */
	private List prepareFilters( Context cx, List dataSetFilters,
			List queryFilters, List temporaryComputedColumns )