Question

我对sql语句有疑问。是否有可能以这种方式进行查询？我需要过滤一个取决于@user_id值的where子句。

ALTER PROCEDURE [dbo].[getUserAddress]
  @user_id int = null
AS

SELECT user_id, state_code, address from UserAddress

IF(@user_id > 10)
BEGIN
 WHERE state_code = 'CA'
END
ELSE
  WHERE address = 'HILLS'
END

我尝试这样做，但似乎不是一种标准方式。

IF(@user_id > 10)
BEGIN
 SELECT user_id, state_code, address from UserAddress WHERE state_code = 'CA'
END
ELSE
   SELECT user_id, state_code, address from UserAddress WHERE address = 'HILLS'
END

请告知这个概念的最佳方法是什么。请帮忙。感谢

Answer 1

您begin后遗漏了else。试试这个：

IF(@user_id > 10)
BEGIN
 SELECT user_id, state_code, address from UserAddress WHERE state_code = 'CA'
END
ELSE
BEGIN
   SELECT user_id, state_code, address from UserAddress WHERE address = 'HILLS'
END

Answer 2

您可以简化：

select 
    user_id, 
    state_code, 
    address 
from 
    UserAddress 
where 
    (@user_id > 10 and state_code = 'CA') or
    (@user_id IS NULL OR (@user_id <= 10 and address = 'HILLS'))

如果您将来添加更多过滤条件，您应该了解参数嗅探。

另外，在(user_id, state_code, address)上创建索引将是此查询的覆盖索引。

Answer 3

您还可以在存储过程中使用动态SQL查询。

<强>查询

declare @sql as varchar(max);
select @sql = 'select * from [UserAddress] ' 
    + stuff((select case when @user_d > 10 
         then 'where state_code= ''CA''' 
         else 'where address = ''Hills''' end  
    for xml path('')), 1,0,'')

 exec(@sql);

Answer 4

而不是这个用法可以在where语句中使用case：

   SELECT user_id, state_code, address from UserAddress WHERE 
   (case when @user_id > 10 then state_code  else address end) 
   = (case when @user_id > 10 then 'CA' else 'HILLS' end)

Answer 5

试试这个

zipWith

Answer 6

你可以简单地......

WHERE
    (@user_id > 10 AND state_code = 'CA')
    OR ((@user_id <= 10 OR @user_id IS NULL) AND address = 'HILLS')

但是，这种方法可能无法产生最佳查询计划。如果结果是一个问题，请使用单独的查询（正如您已经尝试过的那样，但修复了AsheraH建议的语法错误）或动态SQL。

顺便说一句，你可以更简洁地编写单独的查询：

IF @user_id > 10
   SELECT user_id, state_code, address from UserAddress WHERE state_code = 'CA'
ELSE
   SELECT user_id, state_code, address from UserAddress WHERE address = 'HILLS'

Answer 7

你可以试试这个：

ALTER PROCEDURE [dbo]。[getUserAddress]
@user_id int = null
AS
BEGIN

声明@sql nvarchar（5000）
set @sql ='SELECT user_id，state_code，来自UserAddress的地址' IF（@user_id＆gt; 10）
BEGIN
设置@sql = @sql +'WHERE state_code =''CA''' END
ELSE
设置@sql = @sql +'WHERE address =''HILLS''' END

Exec的（@sql）
END

存储过程更改where子句语句

7 个答案: