Question

下午好，

我创建了一个存储函数来模拟＆＃34; SHOW GRANTS FOR＆＃34;的行为。 MySQL中的命令。脚本定义如下：

CREATE FUNCTION get_grants(p_user text, p_host text, p_type text, p_obj text) 
   RETURNS text 
   NOT DETERMINISTIC 
   READS SQL DATA
BEGIN
...
END;

如果我在select语句中使用该函数它正确执行。例如：

SELECT User as USER, Host as HOST, 
      'GLOBAL' as PRIV_TYPE, NULL as DATABASE_NAME,   
       mydatabase.get_grants(User, Host, 'GLOBAL', '') as PRIVILEGES
  FROM mysql.user

但是，当我使用 UNION 或 UNION ALL 语句连接2个用不同参数值调用函数的select语句时，如下所示：

SELECT User as USER, Host as HOST, 
       'GLOBAL' as PRIV_TYPE, NULL as DATABASE_NAME,   
       mydatabase.get_grants(User, Host, 'GLOBAL', '') as PRIVILEGES
  FROM mysql.user
UNION ALL
SELECT User as USER, Host as HOST,
       'DB' as PRIV_TYPE, Db as DATABASE_NAME,
       mydatabase.get_grants(User, Host, 'DB', Db) as PRIVILEGES
  FROM mysql.db
 ORDER BY USER, HOST, DATABASE_NAME IS NULL, DATABASE_NAME;

我收到以下错误：＃1222 - 使用的SELECT语句具有不同的列数。

有人能解释一下这里发生了什么，以及如何解决这个问题？

提前致谢。

Answer 1

我认为导致这个问题的是UNION ALL。通常如果使用UNION ALL，如果列数不同则无关紧要，但UNION必须相同。因此，请尝试使用UNION ALL并将NULL作为DATABASE_NAME删除，或仅使用UNION并将NULL保留为DATABASE_NAME

SELECT User as USER, Host as HOST, 
       'GLOBAL' as PRIV_TYPE, NULL as DATABASE_NAME,   
       mydatabase.get_grants(User, Host, 'GLOBAL', '') as PRIVILEGES
  FROM mysql.user
UNION
SELECT User as USER, Host as HOST,
       'DB' as PRIV_TYPE, Db as DATABASE_NAME,
       mydatabase.get_grants(User, Host, 'DB', Db) as PRIVILEGES
  FROM mysql.db
 ORDER BY USER, HOST, DATABASE_NAME IS NULL, DATABASE_NAME;

OR

SELECT User as USER, Host as HOST, 
       'GLOBAL' as PRIV_TYPE,   
       mydatabase.get_grants(User, Host, 'GLOBAL', '') as PRIVILEGES
  FROM mysql.user
UNION ALL
SELECT User as USER, Host as HOST,
       'DB' as PRIV_TYPE, Db as DATABASE_NAME,
       mydatabase.get_grants(User, Host, 'DB', Db) as PRIVILEGES
  FROM mysql.db
 ORDER BY USER, HOST, DATABASE_NAME IS NULL, DATABASE_NAME;

Answer 2

在几乎油炸我的大脑试图找到问题之后，事实证明实际问题与MySQL提供的错误消息没有任何关系（至少没有提供有关文档中此错误消息的描述）

在这种情况下，错误是在存储函数的实现中。在SELECT ... INTO命令中，我在INTO子句中的两个变量之间缺少“，”。选择的列数与INTO子句中的变量数相对应，问题解决了，我设法在上述查询中使用该函数，没有任何问题。

作为参考，有问题的查询是：

SELECT Select_priv, Insert_priv, Update_priv, Delete_priv,
       Create_priv, Alter_priv, Index_priv, Drop_priv,
       Create_tmp_table_priv, Create_view_priv, Show_view_priv,
       Create_routine_priv, Alter_Routine_priv, Execute_priv, 
       Event_priv, Trigger_priv, Grant_priv, Lock_tables_priv, 
       References_priv
  INTO v_select_priv, v_insert_priv, v_update_priv, v_delete_priv,
       v_create_priv, v_alter_priv, v_index_priv, v_drop_priv,
       v_tmptables_priv, v_createview_priv, v_showview_priv, 
       v_createroutine_priv, v_alterroutine_priv, v_execute_priv,
       v_event_priv, v_trigger_priv, v_grant_priv, v_locktables_priv,
       v_references_priv
  FROM mysql.db
 WHERE User = p_user
   AND Host = p_host
   AND Db = p_obj;

MYSQL：加入包含存储函数的2个select语句时出错

2 个答案: