我正在更新2列和多行。目前我正在运行两个不同的查询来完成这项工作。是否可以在一个查询中完成它?
UPDATE `messages` SET `from_delete` = NOW() WHERE `thread_hash` = 'abc' AND `from_user_id` = '6'
UPDATE `messages` SET `to_delete` = NOW() WHERE `thread_hash` = 'abc' AND `to_user_id` = '6'
答案 0 :(得分:1)
是的,这是可能的,但这很棘手:
UPDATE `messages`
SET `from_delete` = IF(`from_user_id` = '6',NOW(),`from_delete`)
, `to_delete` = IF(`to_user_id` = '6',NOW(),`to_delete` )
WHERE (`thread_hash` = 'abc' AND `from_user_id` = '6')
OR (`thread_hash` = 'abc' AND `to_user_id` = '6')
“技巧”是在赋值中使用条件。如果不应更新该行,则将该列的当前值分配给该列以进行“无更改”操作。
为了完整性,您可能希望将thread_hash上的条件添加到条件。虽然这不会改变查询的任何内容:
UPDATE `messages`
SET `from_delete` = IF(`thread_hash` = 'abc' AND `from_user_id` = '6'
,NOW(),`from_delete`)
, `to_delete` = IF(`thread_hash` = 'abc' AND `to_user_id` = '6'
,NOW(),`to_delete` )
WHERE (`thread_hash` = 'abc' AND `from_user_id` = '6')
OR (`thread_hash` = 'abc' AND `to_user_id` = '6')