Question

我写了下面的查询来更新mysql表

update table1
set val_col = 'TRUE'
where id IN(
SELECT ID  
FROM table1 a INNER JOIN
     table2 b
     ON a.a_id = b.a_id
WHERE a.create_dt >= '2017-01-07' AND
      b.check_status = 'FAIL' AND
      b.check_type = 'check1' AND
      b.timestamp_val = (SELECT MAX(b2.timestamp_val)
                         FROM table2 b2
                         WHERE b2.a_id = b.a_id AND
                               b2.check_status = b.check_status AND
                               b2.check_type = b.check_type
                        ));

我收到错误

You can't specify target table 'table1' for update in FROM clause

Answer 1

错误非常清楚，告诉您，您正在尝试更新table1，但在where子句中也使用了table1。因此，创建一个内部选择和别名它应该可以做到这一点;

update table1
set val_col = 'TRUE'
where id IN(
select * from (
SELECT ID  
FROM table1 a INNER JOIN
     table2 b
     ON a.a_id = b.a_id
WHERE a.create_dt >= '2017-01-07' AND
      b.check_status = 'FAIL' AND
      b.check_type = 'check1' AND
      b.timestamp_val = (SELECT MAX(b2.timestamp_val)
                         FROM table2 b2
                         WHERE b2.a_id = b.a_id AND
                               b2.check_status = b.check_status AND
                               b2.check_type = b.check_type
                        )) aliasTable1);

Answer 2

只需使用JOIN：

UPDATE table1 t1 JOIN
       (SELECT ID  
        FROM table1 a INNER JOIN
             table2 b
             ON a.a_id = b.a_id
        WHERE a.create_dt >= '2017-01-07' AND
              b.check_status = 'FAIL' AND
              b.check_type = 'check1' AND
              b.timestamp_val = (SELECT MAX(b2.timestamp_val)
                                 FROM table2 b2
                                 WHERE b2.a_id = b.a_id AND
                                       b2.check_status = b.check_status AND
                                       b2.check_type = b.check_type
                                )
       ) tt
       ON t1.id = tt.id
    set t1.val_col = 'TRUE';

我怀疑你也可以简化逻辑。

MYSQL：更新表时出错

2 个答案: