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
{
			IQuery.GroupSpec[] groupSpecs = new IQuery.GroupSpec[groups.size( )];
			Iterator it = groups.iterator( );
			for ( int i = 0; it.hasNext( ); i++ )
			{
				IGroupDefinition src = (IGroupDefinition) it.next( );
				if ( ( src.getKeyColumn( ) == null || src.getKeyColumn( )
						.trim( )
						.length( ) == 0 )
						&& ( src.getKeyExpression( ) == null || src.getKeyExpression( )
								.trim( )
								.length( ) == 0 ) )
					throw new DataException( ResourceConstants.BAD_GROUP_EXPRESSION );
				
				String expr = getGroupKeyExpression( src );
				String groupName = "";
				if ( expr.trim( ).equalsIgnoreCase( "row[0]" )
						|| expr.trim( )
								.equalsIgnoreCase( "row._rowPosition" )
						|| expr.trim( ).equalsIgnoreCase( "dataSetRow[0]" )
						|| expr.trim( )
								.equalsIgnoreCase( "dataSetRow._rowPosition" ) )
				{
					groupName = "_{$TEMP_GROUP_" + i + "ROWID$}_";
				}
				else
				{
					groupName = "_{$TEMP_GROUP_" + i + "$}_";
				}