Question

我的应用程序中有4个表：

用户
USESSION
upklist
projshare

最后三个表包含一个名为session_id的字段。

在下面的代码中，括号中的部分用于从session_id表中获取用户“awpeople”的所有usession值。

问题是如何将此结果集读入数组并从数组结果中session_id的所有三个表中删除。

代码：

DELETE FROM usession, 
            upklist, 
            projshar 
WHERE  session_id = (SELECT session_id 
                     FROM   usession 
                     WHERE  delete_session_id IS NULL 
                            AND user_id = (SELECT user_id 
                                           FROM   users 
                                           WHERE  REGEXP_LIKE(USER_NAME, 
                                                  'awpeople', 'i')));

Answer 1

delete一次只能处理一个表格，因此您需要三个语句：

DELETE FROM upklist 
WHERE  session_id = (SELECT session_id 
                     FROM   usession 
                     WHERE  delete_session_id IS NULL 
                            AND user_id = (SELECT user_id 
                                           FROM   users 
                                           WHERE  REGEXP_LIKE(USER_NAME, 
                                                  'awpeople', 'i'))); 

DELETE FROM projshar 
WHERE  session_id = (SELECT session_id 
                     FROM   usession 
                     WHERE  delete_session_id IS NULL 
                            AND user_id = (SELECT user_id 
                                           FROM   users 
                                           WHERE  REGEXP_LIKE(USER_NAME, 
                                                  'awpeople', 'i'))); 

DELETE FROM usession 
WHERE  session_id = (SELECT session_id 
                     FROM   usession 
                     WHERE  delete_session_id IS NULL 
                            AND user_id = (SELECT user_id 
                                           FROM   users 
                                           WHERE  REGEXP_LIKE(USER_NAME, 
                                                  'awpeople', 'i')));

请注意，由于内部查询依赖于usersession，因此您应该从中删除最后。

Answer 2

如果usession在session_id上有唯一或主键，并且其他表具有外键关系，则可以从usession中删除该行，并让数据库将其级联到子表。

Answer 3

多表语法：

删除[LOW_PRIORITY] [QUICK] [IGNORE] tbl_name [。] [，tbl_name [。]] ... FROM table_references [WHERE where_condition]

或者：

删除[LOW_PRIORITY] [QUICK] [IGNORE] FROM tbl_name [。] [，tbl_name [。]] ... 使用table_references [WHERE where_condition]

这来自oracle DELETE documentation。

尝试使用SQL从多个表中删除

3 个答案: