Sql server 2008 单表上的tsql多重更新

是否有基于多个where子句更新表的方法。在一份声明中

update A
set Final = '21'
from StudentTable A
where Student_ID= 4 and bitcm= 0 and receipt= 17



update B
set Final = '22'
from StudentTable B
where Student_ID=4 and bitcm= 0 and receipt =12


update C
set Final ='11'
from StudentTable C
where Student_ID=4 and bitcmp=1 and receipt=17


update D
set Final ='12'
from StudentTable D
where Student_ID=4 and bitcmp=1 and receipt=12

有没有办法将所有这些语句合并成一个语句？

是的，有：

update A
set Final = '21'
from StudentTable A
where Student_ID= 4 and bitcm= 0 and receipt= 17



update B
set Final = '22'
from StudentTable B
where Student_ID=4 and bitcm= 0 and receipt =12


update C
set Final ='11'
from StudentTable C
where Student_ID=4 and bitcmp=1 and receipt=17


update D
set Final ='12'
from StudentTable D
where Student_ID=4 and bitcmp=1 and receipt=12

UPDATE  A
SET     Final = CASE WHEN bitchcm = 0 AND receipt = 17 THEN '21'
                     WHEN bitchcm = 0 AND receipt = 12 THEN '22'
                     WHEN bitchcm = 1 AND receipt = 17 THEN '11'
                     WHEN bitchcm = 1 AND receipt = 12 THEN '12'
                END
FROM    StudentTable A
WHERE   Student_ID = 4 AND   -- the purpose of the three conditions
        bitcm IN (0,1) AND   -- is to speed up the query. It will not
        receipt IN (12,17)   -- scan the whole records on the table

---

如果列

FINAL

为

INT

，则不需要用单引号将值括起来。

如果这些是

学生ID

4的仅有四行，则以下操作有效：

update A
set Final = CASE
    WHEN bitcm=0 and receipt=17 THEN '21'
    WHEN bitcm= 0 and receipt =12 THEN '22'
    WHEN bitcmp=1 and receipt=17 THEN '11'
    WHEN bitcmp=1 and receipt=12 THEN '12'
    END
from StudentTable A
where Student_ID= 4

（我假设

bitcm

和

bitcmp

是同一列，但我不确定使用哪种拼写）

更通用的方法是使用一个表（可能是表变量或参数），其中包含所有必需的键列和新的最终值。然后你会写：

UPDATE A
SET Final = B.Final
FROM StudentTable A
INNER JOIN @AboveMentionedTableVariableOrParameter B
ON
    A.Student_ID = B.Student_ID and
    A.bitcm = b.bitcm and
    A.receipt = b.receipt --And add any other necessary conditions here.

---

你可以用一个案例陈述

UPDATE StudentTable
SET Final = 
 CASE WHEN Student_ID= 4 and bitcm= 0 and receipt= 17 THEN 21
  WHEN Student_ID=4 and bitcm= 0 and receipt =12 THEN 22
  WHEN Student_ID=4 and bitcmp=1 and receipt=17 THEN 11
  WHEN Student_ID=4 and bitcmp=1 and receipt=12 THEN 12
 END
WHERE Student_ID = 4
AND bitcm IN (0,1)
AND receipt IN (12,17) 

---

对最佳方法取决于-除了您显示的4行之外，是否还有其他行用于

Student\u ID

4行？@ypercube这是我想要举个例子的行吗？谢谢

：D

尽管你的建议对这个具体案例是正确的，但整个方法都是错误的。如果一个人决定删除最后一个更新，他也会删除最后一个WHEN语句。但是WHERE子句保持不变，并且仍然匹配我们决定不更新的记录。他们的案例结果将是。。NULL@frikozoid如果他决定删除其中一个更新，他应该更新他的查询。这种方法是100%正确的。JW的工作不是计划将来对一个甚至没有提到的查询所做的更改。@JW。是的，检查结果。你能发现问题吗？@frikozoid如果是这样，那么关于这个问题的最佳更新声明是什么？