mysql的最大严格模式

Question

我有以下查询：

DELETE FROM table1 
WHERE node_id = ".$id." 
AND date < (
      SELECT 
       (MAX(date)- INTERVAL 1 MONTH) 
      from table1 
      WHERE node_id = ".$id." 
) 

然而，由于被启用的MySQL严格的模式我的错误：

ERROR 1093 (HY000): You can't specify target table 'table1' for update in FROM clause 

调查后在线我试图重新作为查询如下：

SELECT 
    * 
FROM table1 as tb1 
INNER JOIN table1 as tb2 
    on tb1.id = tb2.id 
HAVING tb1.date < MAX(tb2.date)-INTERVAL 1 MONTH AND tb1.node_id = 1; 

但是结果集返回空。

我已将max(tb2.date)更改为手动输入的日期，这给了我期待的结果。

任何想法发生了什么？

Answer 1

你可以试试吗？

使用JOIN

数据

mysql> select * from test; 
+---------+------------+ 
| node_id | dt   | 
+---------+------------+ 
|  1 | 2011-03-01 | 
|  1 | 2011-02-01 | 
|  1 | 2011-01-01 | 
+---------+------------+ 
3 rows in set (0.00 sec) 

SELECT

SELECT * 
FROM (
    SELECT MAX(dt) AS max_dt 
    FROM test 
    WHERE node_id = 1 
) x INNER JOIN test ON test.node_id = 1 AND test.dt < x.max_dt; 
+------------+---------+------------+ 
| max_dt  | node_id | dt   | 
+------------+---------+------------+ 
| 2011-03-01 |  1 | 2011-01-01 | 
| 2011-03-01 |  1 | 2011-02-01 | 
+------------+---------+------------+ 

DELETE

DELETE test 
FROM (
    SELECT MAX(dt) AS max_dt 
    FROM test 
    WHERE node_id = 1 
) x INNER JOIN test ON test.node_id = 1 AND test.dt < x.max_dt; 
Query OK, 2 rows affected (0.02 sec) 

检查

mysql> select * from test; 
+---------+------------+ 
| node_id | dt   | 
+---------+------------+ 
|  1 | 2011-03-01 | 
+---------+------------+ 
1 row in set (0.00 sec) 

使用变量

在你的情况，你正在试图删除只有一个NODE_ID。这使得简单的查询。

SELECT @max_dt := MAX(dt) 
FROM test 
WHERE node_id = 1; 
+--------------------+ 
| @max_dt := MAX(dt) | 
+--------------------+ 
| 2011-03-01   | 
+--------------------+ 


DELETE FROM test 
WHERE node_id = 1 
AND dt < @max_dt; 
Query OK, 2 rows affected (0.00 sec) 

BTW

你问17个问题，但没有接受任何的答案。没有有用的答案吗？