Question

SELECT
    vl1.phone_number,
    vl1.first_name,
    CONCAT(
        SUBSTRING(
            (
            SELECT
                vl2.phone_number 
            FROM
                list as vl2
            WHERE
                vl2.phone_number LIKE CONCAT( SUBSTRING( vl1.phone_number FROM 1 FOR 3 ), "%" ) 
            ORDER BY
                RAND( ) 
                LIMIT 1 
            ) 
        FROM
            1 FOR 6 
        ),
        FLOOR( RAND( ) * ( 8999 ) ) + 1000 
    ) AS autogenNumber 
FROM
    list as vl1
LIMIT 1

我得到的结果是

phone_number | firstname | autogenNumber

autogenNumber是通过首先搜索共享前三个数字的其他编号来生成的。然后从该数字中选出6个数字，然后将另外4个随机数字替换为末尾。

上面的sql查询完全根据我的需要生成自动生成号。

但是，现在，当我想使用下面的类似查询更新此列表中的列security_phrase时，就会出现此问题。

UPDATE list as vl1
SET vl1.security_phrase = (
    CONCAT(
        SUBSTRING(
            (
                SELECT
                    vl2.phone_number 
                FROM
                    list AS vl2 
                WHERE
                    vl2.phone_number LIKE CONCAT( SUBSTRING(phone_number FROM 1 FOR 3 ), "%" ) 
                ORDER BY
                    RAND( ) 
                    LIMIT 1 
                ) 
            FROM
                1 FOR 6 
            ),
            FLOOR( RAND( ) * ( 8999 ) ) + 1000 
        ) 
    ) 
    LIMIT 10

给我一个错误：

1093-表'vl1'被指定了两次，均作为'UPDATE'的目标并作为单独的数据源

我也尝试过

UPDATE list AS vl1
JOIN list AS vl2 

SET vl1.security_phrase = (
    CONCAT( SUBSTRING( vl2.phone_number FROM 1 FOR 6 ), FLOOR( RAND( ) * ( 8999 ) ) + 1000 ) 
) 
WHERE
    vl2.phone_number LIKE CONCAT( SUBSTRING( vl1.phone_number FROM 1 FOR 3 ), "%" )

不起作用，也没有得到预期的结果...

任何帮助

Answer 1

MySQL不允许在另一个子查询中再次引用表正在更新，除非位于FROM子句（Derived Table中）。

现在，在您的特殊情况下，我们需要将完整的SELECT查询块放入“派生表”中。如聊天中所述，lead_id是您的主键，因此我们将使用PK重新加入以相应地更新行。

UPDATE list AS t1 
JOIN 
(
  SELECT
    vl1.lead_id,
    CONCAT(
        SUBSTRING(
            (
            SELECT
                vl2.phone_number 
            FROM
                list as vl2
            WHERE
                vl2.phone_number LIKE CONCAT( SUBSTRING( vl1.phone_number FROM 1 FOR 3 ), "%" ) 
            ORDER BY
                RAND( ) 
                LIMIT 1 
            ) 
        FROM
            1 FOR 6 
        ),
        FLOOR( RAND( ) * ( 8999 ) ) + 1000 
    ) AS autogenNumber 
  FROM
    list as vl1
) AS dt 
  ON dt.lead_id = t1.lead_id 
SET t1.security_phrase = dt.autogenNumber

在子查询中使用同一表的UPDATE语句

1 个答案: