Sql 有什么区别？

我想计算tlp中但不在gal中的用户数。为此，我有下一个代码：

select count(*) 
from tlp
where ((not EXISTS (SELECT mail 
                    FROM glob
                    WHERE tlp.email1 = glob.mail) 
        AND tlp.email1 IS NOT NULl)
         or ( not EXISTS (SELECT LOGIN
                         FROM   glob 
                         WHERE  tlp.userid = glob.LOGIN     
                        ) 
                        and tlp.email1 is null));

当我运行此命令时，我收到688个用户，当我想用此代码删除这些用户时：

Delete from tlp
  where (( not EXISTS (SELECT mail 
                     FROM   glob 
                     WHERE    tlp.email1 = glob.mail  ) 
         AND tlp.email1 IS NOT NULl)
         or ( not EXISTS (SELECT Login 
                         FROM   glob 
                         WHERE  tlp.userid = glob.login    
                        ) 
                        and tlp.email1 is null));

我删除了672行。

---

我看不出问题所在

这种方法更简单

select count(*) from 
(
select idField
from etc -- 
minus
select idField
from etc -- these are the records you want to exclude
) derivedTable

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您可以计算出详细信息。

数据是否在选择和删除之间发生了更改？这是可复制的吗？