mysql锁错误还是错误？

Question

我们走了：

mysql> LOCK TABLES radcheck WRITE;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT * FROM radcheck WHERE id NOT IN (
    ->     SELECT id FROM (
    ->         SELECT id FROM radcheck  WHERE attribute = 'Password' GROUP BY UserName HAVING COUNT(*) > 1
    ->      ) AS c
    -> );
ERROR 1100 (HY000): Table 'radcheck' was not locked with LOCK TABLES

WTF？

修改

SET AUTOCOMMIT = 0
    -> ;
Query OK, 0 rows affected (0.00 sec)

mysql> LOCK TABLES radcheck WRITE;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT * FROM radcheck WHERE id NOT IN ( SELECT id FROM radcheck  WHERE attribute = 'Password' GROUP BY UserName HAVING COUNT(*) > 1 );
ERROR 1100 (HY000): Table 'radcheck' was not locked with LOCK TABLES



mysql> LOCK TABLES radcheck READ;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT * FROM radcheck WHERE id NOT IN ( SELECT id FROM radcheck  WHERE attribute = 'Password' GROUP BY UserName HAVING COUNT(*) > 1 );
ERROR 1100 (HY000): Table 'radcheck' was not locked with LOCK TABLES

pd：如果我没有锁定表，查询工作正常。 pd：这只是一个例子，简化问题..在现实生活中是一个DELETE ......

Answer 1

使用锁定表时，需要锁定查询中的所有表。 使用子查询时，它会创建一个表。而你没有锁定它。 因为你得到了错误。

参考： http://dev.mysql.com/doc/refman/5.0/en/lock-tables.html

为内表提供别名

测试样本：

lock tables products as p1 write, products as p2 write ;
select product_id  from products as p1
where product_id  not in ( 
select product_id from products p2 where product_id in (1,2)
) 

可能你需要这个：

lock tables radcheck as r1 write, radcheck as r2 write ;

 SELECT * FROM radcheck r1 WHERE id NOT IN (
SELECT id FROM (
  SELECT id FROM radcheck r2 WHERE attribute = 'Password' GROUP BY UserName HAVING COUNT(*) > 1) AS c
 );

Answer 2

可能你有autocommit = 1并在提交后释放表。

尝试：

SET AUTOCOMMIT = 0

开始交易之前。

http://dev.mysql.com/doc/refman/5.0/es/innodb-and-autocommit.html

Answer 3

您正在锁定WRITE的表格。您需要锁定READ的表，因为您正在使用只从表中读取的SELECT。

但是你不应该真正锁定表，因为这会阻止并发。

修改

您还需要使用别名，因为在查询中使用同一个表两次。

即

LOCK TABLES radcheck AS read1 READ, radcheck AS read2 READ;
SELECT * 
FROM radcheck AS read1
WHERE id NOT IN
   (
       SELECT id FROM radcheck AS read2
       WHERE attribute = 'Password'
       GROUP BY UserName
       HAVING COUNT(*) > 1
   );