在MySQL中使用subselect更新

Question

如何让以下语句在MySQL中运行？

UPDATE my_table t1 SET column_1 = 
(SELECT column_1 FROM my_table t2 WHERE t2.id = (t1.id - 1))
WHERE t1.type = 2

我收到"You can't specify target table 't1' for update in FROM clause"错误。

Answer 1

您可以使用加入进行更新：

UPDATE my_table t1
    JOIN my_table t2 ON t2.id = t1.id - 1
SET t1.column_1 = t2.column_1
WHERE t1.type = 2

Answer 2

尝试删除“my_table”：）

UPDATE t1 SET column_1 = 
(SELECT column_1 FROM t2 WHERE t2.id = (t1.id - 1))
WHERE t1.type = 2