Question

如果元组是我正在讨论的术语，我不是100％，但我正在看这样的事情：

Table grades
user    grade
------------
Jim     B
Bill    C
Tim     A
Jim     B+

我知道我能做到：

SELECT COUNT(*)
FROM grades
WHERE (
   (user = 'Jim' AND grade = 'B')
   OR (user = 'Tim' AND grade = 'C')
);

但有没有办法做更像这样的事情？

SELECT COUNT(*)
    FROM grades
    WHERE (user, grade) IN (('Jim','B'), ('Tim','C'));

编辑：作为旁注，我只测试过：

(user, grade) = ('Tim','C')

那就失败了，所以我认为IN也会失败，但我错了（谢天谢地！）。

Answer 1

您发布的查询应该是有效的语法

SQL> ed
Wrote file afiedt.buf

  1  with grades as (
  2    select 'Jim' usr, 'B' grade from dual
  3    union all
  4    select 'Bill', 'C' from dual
  5    union all
  6    select 'Tim', 'A' from dual
  7    union all
  8    select 'Jim', 'B+' from dual
  9  )
 10  select *
 11    from grades
 12   where (usr,grade) in (('Jim','B'),
 13                         ('Tim','C'),
 14*                        ('Tim','A'))
SQL> /

USR  GR
---- --
Jim  B
Tim  A

Answer 2

您可以使用子查询来处理像表一样的元组列表：

SELECT  COUNT(*)
FROM    grades
JOIN    (
        SELECT  'Jim' as user, 'B' as grade from dual
        UNION ALL
        SELECT  'Tim', 'C' from dual
        UNION ALL
        SELECT  'Pim', 'D' from dual
        ) as SearchTarget
ON      SearchTarget.user = grades.user
        and SearchTarget.grade = grades.grade

是否有可能比较oracle兼容的sql中的元组？

2 个答案: