如果参数为空，SQL 将忽略 WHERE 的一部分 [英] SQL ignore part of WHERE if parameter is null

问题描述

我有一个基于 4 个参数从表中获取信息的存储过程.

I have a stored procedure that fetches info from a table based on 4 parameters.

我想根据参数获取值，但如果参数为 NULL，则不会检查该参数.因此，如果所有 4 个参数都为空，我将显示整个表格.

I want to get values based on the parameters, but if a parameter is NULL then that parameter isn't checked. So if all 4 parameters is null I would show the entire table.

这是我的 SP(如您所见，这只适用于 1 个参数 atm):

This is my SP (as you can see, this only works for 1 parameter atm):

CREATE PROCEDURE myProcedure
    @Param1 nvarchar(50),
    @Param2 nvarchar(50),
    @Param3 nvarchar(50),
    @Param4 nvarchar(50)
AS
BEGIN
    IF(@Param1 IS NULL)
        BEGIN
            SELECT Id, col1, col2, col3, col4 FROM myTable
        END
    ELSE
        BEGIN
            SELECT Id, col1, col2, col3, col4 FROM myTable WHERE col1 LIKE @Param1+'%'
        END
END

有没有什么方法可以为每个可能的组合(15个IF)设置IF?

Is there some way to do this without having a IF for every possible combination (15 IFs)?

推荐答案

怎么样

SELECT Id, col1, col2, col3, col4 
FROM    myTable 
WHERE   col1 LIKE @Param1+'%'
OR      @Param1 IS NULL

在这种特定情况下，您也可以使用

in this specific case you could have also used

SELECT Id, col1, col2, col3, col4 
FROM    myTable 
WHERE   col1 LIKE ISNULL(@Param1,'')+'%'

但总的来说你可以尝试类似的东西

But in general you can try something like

SELECT Id, col1, col2, col3, col4 
FROM    myTable 
WHERE   (condition1 OR @Param1 IS NULL)
AND     (condition2 OR @Param2 IS NULL)
AND     (condition3 OR @Param3 IS NULL)
...
AND     (conditionN OR @ParamN IS NULL)

这篇关于如果参数为空，SQL 将忽略 WHERE 的一部分的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！