Question

我有两张桌子，任务和动作。 actions有两列，created_at和updated_at。任务有一个列started_at

我该怎么做

SELECT MAX( UNIX_TIMESTAMP( tasks.started_at ) ) AS started_at, action . * 
FROM tasks, action
WHERE UNIX_TIMESTAMP( action.created_at ) > started_at
OR UNIX_TIMESTAMP( action.updated_at ) > started_at

尝试选择比MAX更多的created_at或updated_at的所有操作（tasks.started_at）

Answer 1

SELECT * FROM actions 
WHERE created_at>(SELECT MAX(started_at) FROM tasks) OR
      updated_at>(SELECT MAX(started_at) FROM tasks)

不要担心性能，默认情况下MySQL应该缓存SELECT MAX(started_at) FROM tasks值。如果您有其他配置，请将SQL_CACHE添加到主查询：SELECT SQL_CACHE * FROM...

根据日期选择行

1 个答案: