Question

我正在创建一个存储过程，该存储过程从存储项目资金的表中获取值（他们的id，他们的目标以及他们到目前为止收到的内容） proc将返回已完全资助的项目ID或未提供参数@QueryType的项目ID，但我不知道如何在where中添加if条件，I只在陈述的select部分使用过它们。

这是我到目前为止所做的，但它只是给了我INCORRECT SYNTAX第一个案例：

--create proc Projects.GetFundedProjects -- Projects that have reached their goal
create proc Projects.GetFundedProjects
(@QueryType int
)
as
begin
select * from Stats.FundedProjectsToday
CASE 
WHEN @QueryType = 1 -- Projects that reached their goal
THEN
     where AUReceived=>ProjectGoal
WHEN @QueryType = 2 -- Projects that have not been funded
THEN 
    where AUReceived<ProjectGoal
end --end the case
end -- end the proc

Answer 1

WHERE关键字只能出现一次，并且出现在FROM子句之后。

SELECT * 
FROM   Stats.FundedProjectsToday
WHERE  CASE 
         WHEN @QueryType = 1 -- Projects that reached their goal
           THEN AUReceived >= ProjectGoal
         WHEN @QueryType = 2 -- Projects that have not been funded
           THEN AUReceived < ProjectGoal
       END

可选地

SELECT * 
FROM   Stats.FundedProjectsToday
WHERE  CASE @QueryType
         WHEN 1 -- Projects that reached their goal
           THEN AUReceived >= ProjectGoal
         WHEN 2 -- Projects that have not been funded
           THEN AUReceived < ProjectGoal
       END

可能会早点写出

SELECT * 
FROM Stats.FundedProjectsToday
WHERE (@QueryType = 1 AND AUReceived >= ProjectGoal)
OR    (@QueryType = 2 AND AUReceived < ProjectGoal)

或

SELECT * 
FROM Stats.FundedProjectsToday
WHERE @QueryType = 1 
AND   AUReceived >= ProjectGoal
UNION ALL
SELECT * 
FROM Stats.FundedProjectsToday
WHERE @QueryType = 2 
AND   AUReceived < ProjectGoal

Answer 2

对每个@QueryType值使用互斥条件：

select * 
from Stats.FundedProjectsToday
where (@QueryType = 1 and AUReceived >= ProjectGoal)
   or (@QueryType = 2 and AUReceived < ProjectGoal)

顺便说一下，greater or equal operator写为>=，而不是=>。

SQL-Server：在where运算符

2 个答案: