直接上图:

想把PARENT_ORDER 字段值改为IS_ORDER值相同的ID。
IS_ORDER是PARENT_ORDER 上级。
------解决思路----------------------
update tableName set PARENT_ORDER =IS_ORDER where 1=1;
------解决思路----------------------
update table_name a set a.PARENT_ORDER=(select b.id from table_name where a.PARENT_ORDER=b.IS_ORDER)
------解决思路----------------------
update tableName a, tableName b set a.PARENT_ORDER = b.ID where a.IS_ORDER = b.PARENT_ORDER;
------解决思路----------------------
update table_name a set a.PARENT_ORDER=(select b.id from table_name where a.PARENT_ORDER=b.IS_ORDER) 帮顶这个方法