Question

假设有一个存储过程有3个参数。在所有可能性中，我希望通过单个WHERE子句实现此目的，而不会过度使用() AND () OR () ...

示例：

    //Params
@CITY VARCHAR(100) = NULL,
@GENDER VARCHAR(100) = NULL,
@AGE VARCHAR(100) = NULL

我认为你可以使用IF BEGIN ... END为每个变量（如果存在）执行此操作，但这会使代码比预期更长。

下面这个方法不会起作用，因为它的方式太长了（大概有10个不同的字段，但这个例子只有3个。）而且我不确定它是否甚至直接提取了不同的值...

SELECT NAME FROM TABLE 
WHERE (
(CITY=@CITY AND GENDER=@GENDER AND AGE=@AGE)
OR (CITY=@CITY AND GENDER=@GENDER)
OR (GENDER=@GENDER AND AGE=@AGE)
OR (CITY=@CITY AND AGE=@AGE)
OR (CITY=@CITY)
OR (GENDER=@GENDER)
OR (AGE=@AGE)
)

是否有更短效的方法来做到这一点？

如果是，则该方法最好也与JOIN兼容。

Answer 1

除ISNULL / COALESCE选项外，您可以测试参数为null：

SELECT NAME  
FROM TABLE  
WHERE  
    (@City IS NULL OR City = @City)
AND 
    (@Gender IS NULL OR Gender = @Gender)
AND 
    (@Age IS NULL OR Age = @Age)

Answer 2

这是怎么回事？

SELECT
    NAME
FROM TABLE 
WHERE CITY = COALESCE(@CITY, CITY)
    AND GENDER = COALESCE(@GENDER, GENDER)
    AND AGE = COALESCE(@AGE, AGE)

Answer 3

尝试这样的事情：

SELECT NAME 
FROM TABLE 
WHERE 
    City = IsNull(@City, City) AND
    Gender = IsNull(@Gender, Gender) AND
    Age = IsNull(@Age, Age)

OR：

SELECT NAME 
FROM TABLE 
WHERE 
    (City = @City OR @City IS NULL) AND
    (Gender = @Gender OR @Gender IS NULL) AND
    (Age = @Age OR @Age IS NULL)

Answer 4

SELECT NAME   
FROM TABLE   
WHERE       
  City = case when isnull(@City ,'') = '' then City
                        else @City end
AND      
  Gender = case when isnull(@Gender ,'') = '' then Gender
                        else @Gender end
AND  
  Age = case when isnull(@Age ,0) = 0 then Age
                        else @Age end

Answer 5

可能是这样的：

create procedure myProc
    --Params
@CITY VARCHAR(100) = NULL,
@GENDER VARCHAR(100) = NULL,
@AGE VARCHAR(100) = NULL
as

SELECT NAME FROM [TABLE]
WHERE ISNULL(CITY,'')=ISNULL(@CITY,ISNULL(CITY,''))
AND ISNULL(GENDER,'')=ISNULL(@GENDER,ISNULL(GENDER,''))
AND ISNULL(AGE,'')=ISNULL(@AGE,ISNULL(AGE,''))
go

假设WHERE子句中的列可以为空，使用ISNULL避免空值比较。

WHERE子句中的可选参数

5 个答案: