sql-server - 在 1 个表上有 2 个字段的子句

Question

我有一个查询：

 SELECT 
   MAX(date), 
   logId,
   computerId
 FROM 
   logTable
 WHERE logId IN ('1','2','3')

但我希望 IN 子句也像这样测试 computerId ：

logId = '1'和computerId = '998874',

logId = '2'和computerId = '334211', ...

这该怎么做 ？

Answer 1

您必须IN用多个OR语句替换该语句

 SELECT  MAX(date)
        ,  logId
        , computerId
 FROM   logTable
 WHERE  (logId = '1' AND computerid = '998874')
        OR (logId = '2' AND computerid = '334211')

或者，如果您有许多条件，则为它们创建一个内存表并在这些条件上连接可能更具可读性

;WITH Conditions (logID, computerid) AS (
  SELECT '1', '998874'
  UNION ALL SELECT '2', '334211'
)
SELECT  MAX(date)
        ,  logId
        , computerId
FROM   logTable lt
       INNER JOIN Conditions c ON c.logID = lt.LogID 
                                  AND c.computerid = lt.computerID

Answer 2

我不认为你可以用一个IN子句来做到这一点。我认为你需要一个条件 where 。所以：

SELECT MAX(date), logId, computerId
FROM logTable
WHERE (logId = 1 AND computerId = '998874') OR
      (logId = 2 AND computerId = '334211') OR
      ...

Answer 3

IN在 SQL Server 中不支持元组。您可以使用EXISTS和表表达式。2008 语法如下。

SELECT MAX(l.date),
       l.logId,
       l.computerId
FROM   logTable l
WHERE  EXISTS(SELECT *
              FROM   (VALUES ( '1', '998874'),
                              ('2', '334211')) v(logId, computerId)
              WHERE  v.computerId = l.computerId
                     AND v.logId = l.logId)  
GROUP  BY l.logId,
          l.computerId  

Answer 4

像这样：

SELECT 
   MAX(date), 
   logId,
   computerId
 FROM 
   logTable
 WHERE (logId = '1' AND computerId = '998874')
    OR (logId = '2' AND computerId = '334211')
    OR (logId = '3' AND computerId = '123456')
 GROUP BY logId, computerId