1DELETE `tiki_object_relations`
2FROM `tiki_object_relations`
3	LEFT JOIN `tiki_sheets` `ps` on `ps`.`sheetId` = `tiki_object_relations`.`source_itemId`
4	LEFT JOIN `tiki_sheets` `cs` on `cs`.`sheetId` = `tiki_object_relations`.`target_itemId`
5WHERE
6	(
7		ISNULL(`ps`.`sheetId`)
8		OR ISNULL(`cs`.`sheetId`)
9	)
10	AND `tiki_object_relations`.`source_type` = 'sheetId'
11