if else语句设置条件（SQL）

Question

只是想知道，是否有原因，为什么下面的代码不起作用？我试图更新2列值，如果他们达到多个标准，但我得到一个错误，说'关键字附近的错误语法'如果'和'总'附近的语法不正确。任何帮助非常感谢！

update [dbo].[wages table] 
IF([criteria1]='AA1' and [criteria2]='50yrs and below' and [criteria3]= 'X<=50') 
set [Total ] = '0', [Employee ]='0' else 
if ([criteria1]='AA1' and [criteria2]='50yrs and below' and [criteria3]= 'X<=50') 
set [Total ] = '10', [Employee ]='10' else 
if ([criteria1]='AA1' and [criteria2]='50yrs and below' and [criteria3]= 'X<=50') 
set [Total ] = '20', [Employee ]='20' else 
if ([criteria1]='AA1' and [criteria2]='50yrs and below' and [criteria3]= 'X<=50') 
set [Total ] = '30', [Employee ]='30' else 
set [Total ] = 'NULL', [Employee ]='NULL' 

Answer 1

我想这是你正在尝试做的：

UPDATE [dbo].[wages table] 
    SET [Total] = CASE [criteria3] WHEN 'X<=50' THEN '0' ELSE 'NULL' END, 
    SET [Employee] = CASE [criteria3] WHEN = 'X<=50' THEN '0' ELSE 'NULL' END 
WHERE [criteria1]='AA1' and [criteria2]='50yrs and below' 

如果criteria1和criteria2是相同的所有那么您可以在WHERE条款检查。我相信区别在于criteria3。

是这样的：

UPDATE [dbo].[wages table] 
    SET [Total] = CASE [criteria3] WHEN 'X<=50' THEN '0' WHEN 'X<=40' THEN 1 WHEN 'X<=30' THEN 3 ELSE 'NULL' END, 
    SET [Employee] = CASE [criteria3] WHEN 'X<=50' THEN '0' WHEN 'X<=40' THEN 1 WHEN 'X<=30' THEN 3 ELSE 'NULL' END 
WHERE [criteria1]='AA1' and [criteria2]='50yrs and below' 

Answer 2

在SQL您可以在CASE表达这种类型的语句：

UPDATE [dbo].[wages table] 
SET [Total] = CASE WHEN ([criteria1]='AA1' AND [criteria2]='50yrs and below' AND [criteria3]= 'X<=50') THEN '0' 
        WHEN ([criteria1]='AA1' AND [criteria2]='50yrs and below' AND [criteria3]= 'X<=50') THEN '0' 
        WHEN ([criteria1]='AA1' AND [criteria2]='50yrs and below' AND [criteria3]= 'X<=50') THEN '0' 
        ELSE NULL END, 
    [Employee ] = CASE WHEN ([criteria1]='AA1' AND [criteria2]='50yrs and below' AND [criteria3]= 'X<=50') THEN '0' 
        WHEN ([criteria1]='AA1' AND [criteria2]='50yrs and below' AND [criteria3]= 'X<=50') THEN '0' 
        WHEN ([criteria1]='AA1' AND [criteria2]='50yrs and below' AND [criteria3]= 'X<=50') THEN '0' 
        ELSE NULL END 

除此之外，我看不到你的情况有什么区别。