如何在SQL SELECT语句中执行IF…THEN?
例如:
SELECT IF(Obsolete = 'N' OR InStock = 'Y' ? 1 : 0) AS Saleable, * FROM Product
如何在SQL SELECT语句中执行IF…THEN?
例如:
SELECT IF(Obsolete = 'N' OR InStock = 'Y' ? 1 : 0) AS Saleable, * FROM Product
当前回答
CASE语句最接近SQL中的IF,并且在所有版本的SQL Server上都受支持。
SELECT CAST(
CASE
WHEN Obsolete = 'N' or InStock = 'Y'
THEN 1
ELSE 0
END AS bit) as Saleable, *
FROM Product
如果希望结果为布尔值,则只需使用CAST运算符。如果您对int感到满意,这将起作用:
SELECT CASE
WHEN Obsolete = 'N' or InStock = 'Y'
THEN 1
ELSE 0
END as Saleable, *
FROM Product
CASE语句可以嵌入到其他CASE语句中,甚至可以包含在聚合中。
SQL Server Denali(SQL Server 2012)添加了IIF语句,该语句也可用于访问(Martin Smith指出):
SELECT IIF(Obsolete = 'N' or InStock = 'Y', 1, 0) as Saleable, * FROM Product
其他回答
Microsoft SQL Server(T-SQL)
在选择中,使用:
select case when Obsolete = 'N' or InStock = 'Y' then 'YES' else 'NO' end
在where子句中,使用:
where 1 = case when Obsolete = 'N' or InStock = 'Y' then 1 else 0 end
对于使用SQL Server 2012的用户来说,IIF是一个已添加的功能,可以作为Case语句的替代。
SELECT IIF(Obsolete = 'N' OR InStock = 'Y', 1, 0) AS Salable, *
FROM Product
您可以有两种选择来实现:
使用从SQL Server 2012引入的IIF:选择IIF((过时=“N”或InStock=“Y”),1,0)作为可销售产品,*来自产品使用Select Case:选择大小写当过时=“N”或InStock=“Y”时然后1其他0结束销售*FROM产品
SELECT 1 AS Saleable, *
FROM @Product
WHERE ( Obsolete = 'N' OR InStock = 'Y' )
UNION
SELECT 0 AS Saleable, *
FROM @Product
WHERE NOT ( Obsolete = 'N' OR InStock = 'Y' )
case statement some what similar to if in SQL server
SELECT CASE
WHEN Obsolete = 'N' or InStock = 'Y'
THEN 1
ELSE 0
END as Saleable, *
FROM Product