我想使用CASE语句更新SQLServer2005中的一些记录

语句为此目的工作，但else条件扫描表中的每条记录。有没有办法让未受影响的行保持原样？

添加一个

WHERE

子句

UPDATE dbo.TestStudents  
SET LASTNAME = 
( CASE  
WHEN (LASTNAME = 'AAA') THEN 'BBB' 
WHEN (LASTNAME = 'CCC') THEN 'DDD' 
WHEN (LASTNAME = 'EEE') THEN 'FFF' 
ELSE  (LASTNAME)
END )

---

如果您不想重复列表两次（根据@J W的回答），则将更新放在一个表变量中，并在

更新中使用
连接
：

UPDATE dbo.TestStudents  
SET     LASTNAME =  CASE  
                        WHEN LASTNAME = 'AAA' THEN 'BBB' 
                        WHEN LASTNAME = 'CCC' THEN 'DDD' 
                        WHEN LASTNAME = 'EEE' THEN 'FFF' 
                        ELSE LASTNAME
                    END 
WHERE   LASTNAME IN ('AAA', 'CCC', 'EEE')

当

declare @ToDo table (FromName varchar(10), ToName varchar(10))
insert into @ToDo(FromName,ToName) values
 ('AAA','BBB'),
 ('CCC','DDD'),
 ('EEE','FFF')

update ts set LastName = ToName
from dbo.TestStudents ts
       inner join
     @ToDo t
       on
         ts.LastName = t.FromName

我喜欢在不允许重复值的情况下使用临时表，您的更新可能会创建它们。例如：

UPDATE [dbo].[JobTemplates]
SET [CycleId] = 
    CASE [Id]
        WHEN 1376 THEN 44   --ACE1 FX1
        WHEN 1385 THEN 44   --ACE1 FX2
        WHEN 1574 THEN 43   --ACE1 ELEM1
        WHEN 1576 THEN 43   --ACE1 ELEM2
        WHEN 1581 THEN 41   --ACE1 FS1
        WHEN 1585 THEN 42   --ACE1 HS1
        WHEN 1588 THEN 43   --ACE1 RS1
        WHEN 1589 THEN 44   --ACE1 RM1
        WHEN 1590 THEN 43   --ACE1 ELEM3
        WHEN 1591 THEN 43   --ACE1 ELEM4
        WHEN 1595 THEN 44   --ACE1 SSTn     
        ELSE 0  
     END
WHERE
    [Id] IN (1376,1385,1574,1576,1581,1585,1588,1589,1590,1591,1595)

SELECT
     [Id]
    ,[QueueId]
    ,[BaseDimensionId]
    ,[ElastomerTypeId]
    ,CASE [CycleId]
        WHEN  29 THEN 44
        WHEN  30 THEN 43
        WHEN  31 THEN 43
        WHEN 101 THEN 41
        WHEN 102 THEN 43
        WHEN 116 THEN 42
        WHEN 120 THEN 44
        WHEN 127 THEN 44
        WHEN 129 THEN 44
        ELSE    0
     END                AS [CycleId]
INTO
    ##ACE1_PQPANominals_1
FROM 
    [dbo].[ProductionQueueProcessAutoclaveNominals]
WHERE
    [QueueId] = 3
ORDER BY 
    [BaseDimensionId], [ElastomerTypeId], [Id];
---- (403 row(s) affected)

UPDATE [dbo].[ProductionQueueProcessAutoclaveNominals]
SET 
    [CycleId] = X.[CycleId]
FROM
    [dbo].[ProductionQueueProcessAutoclaveNominals]
INNER JOIN
(
    SELECT  
        MIN([Id]) AS [Id],[QueueId],[BaseDimensionId],[ElastomerTypeId],[CycleId] 
    FROM 
        ##ACE1_PQPANominals_1
    GROUP BY    
        [QueueId],[BaseDimensionId],[ElastomerTypeId],[CycleId] 
) AS X
ON
    [dbo].[ProductionQueueProcessAutoclaveNominals].[Id] = X.[Id];
----(375 row(s) affected)