创建视图时出错

Question

我收到了错误#1349 - View's SELECT contains a subquery in the FROM clause

我的代码是：

CREATE VIEW `MyViewName` AS
SELECT *
FROM
  (SELECT *
   FROM (
           (SELECT *
            FROM `crm_clients`
            WHERE ctype=1
            ORDER BY rand() LIMIT 0,
                                  3)
         UNION
           (SELECT *
            FROM `crm_clients`
            WHERE ctype=1
            ORDER BY rand() LIMIT 0,
                                  3)
         UNION
           (SELECT *
            FROM `crm_clients`
            WHERE ctype=1
            ORDER BY rand() LIMIT 0,
                                  3)
         UNION
           (SELECT *
            FROM `crm_clients`
            WHERE ctype=1
            ORDER BY rand() LIMIT 0,
                                  3)) t
   ORDER BY rand())

这段代码有什么问题？我不熟悉视图

Answer 1

当您定义视图时，MySQL 不允许在 from 子句中使用子查询。

你可以做你想做的事：

Create View `MyViewName` as
    (SELECT * FROM `crm_clients` WHERE ctype=1 order by rand() limit 0,3)
    union 
    (SELECT * FROM `crm_clients` WHERE ctype=1 order by rand() limit 0,3)
    union
    (SELECT * FROM `crm_clients` WHERE ctype=1 order by rand() limit 0,3)
    union
    (SELECT * FROM `crm_clients` WHERE ctype=1 order by rand() limit 0,3)
    order by rand();

我的猜测是您实际上也想更改 ctype 值。否则查询就比较奇怪了。

Here 是对视图的限制。