sql 使用where筛选时,字段空时,不做筛选,非空时筛选

落日映苍穹つ 2021-11-09 21:26 650阅读 0赞

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### 需求说明: ###

1.查询“Name=赵” 且“Tel=180xxxxxxxx” 且“Address=西安预立数据科技有限责任公司“ 且“Email=155154xxx@qq.com”  
2.当Name或Tel或Address或Email为空时不做筛选

###    方法一： ###

这种方法可以达到目的，但是sql语句不易扩展和维护,不推荐使用

SELECT TOP 1000 [Id]
          ,[Name]
          ,[Tel]
          ,[Address]
          ,[Email]
      FROM [hlltest].[dbo].[User]
      WHERE 
      (name = @name AND  Tel IS NULL AND Address IS NULL AND Email IS NULL)
      OR (name IS NULL  AND  Tel = @Tel AND Address IS NULL AND Email IS NULL)
      OR (name IS NULL  AND  Tel IS NULL AND Address = @Address AND Email IS NULL)
      OR (name IS NULL  AND  Tel IS NULL AND Address IS NULL AND Email = @Email)
    
      OR (name = @name  AND  Tel = @Tel AND Address IS NULL AND Email IS NULL)
      OR (name = @name  AND  Tel IS NULL AND Address = @Address AND Email IS NULL)
      ---还有很多种组合条件.....

### 方法二： ###

--推荐使用isnull

DECLARE @name NVARCHAR(50) = '赵'
      ,@Tel NVARCHAR(50) = '180xxxxxxxx'
      ,@Address NVARCHAR(50) = '西安预立数据科技有限责任公司'
      ,@Email NVARCHAR(50) = '155154xxx@qq.com'
    
      SELECT TOP 1000 [Id]
          ,[Name]
          ,[Tel]
          ,[Address]
          ,[Email]
      FROM [hlltest].[dbo].[User]
      WHERE ISNULL(name,@name) = @name
      AND ISNULL(Tel,@Tel) = @Tel
      AND ISNULL(Address,@Address) = @Address
      AND ISNULL(Email,@Email) = @Email

###    **当Name,Tel,Address,Email存放是字符串空时，Isnull就不能使用, 可以使用case when 或 LEN 判断** ###

###    方法一： ###

--使用case when

DECLARE @name NVARCHAR(50) = '赵'
      ,@Tel NVARCHAR(50) = '180xxxxxxxx'
      ,@Address NVARCHAR(50) = '西安预立数据科技有限责任公司'
      ,@Email NVARCHAR(50) = '155154xxx@qq.com'
    
      SELECT TOP 1000 [Id]
          ,[Name]
          ,[Tel]
          ,[Address]
          ,[Email]
      FROM [hlltest].[dbo].[User]
      WHERE (1 = (CASE WHEN Name = ''  THEN 1 ELSE 0 END) OR  Name = @name )
      AND (1 = (CASE WHEN Tel = ''  THEN 1 ELSE 0 END) OR  Tel = @Tel )
      AND (1 = (CASE WHEN Address = ''  THEN 1 ELSE 0 END) OR  Address = @Address )
      AND (1 = (CASE WHEN Email = ''  THEN 1 ELSE 0 END) OR  Email = @Email )

###    方法二： ###

\--使用LEN

DECLARE @name NVARCHAR(50) = '赵'
      ,@Tel NVARCHAR(50) = '180xxxxxxxx'
      ,@Address NVARCHAR(50) = '西安预立数据科技有限责任公司'
      ,@Email NVARCHAR(50) = '155154xxx@qq.com'
    
      SELECT TOP 1000 [Id]
          ,[Name]
          ,[Tel]
          ,[Address]
          ,[Email]
      FROM [hlltest].[dbo].[User]
      WHERE (LEN(Name) = 0 OR  Name = @name )
      AND (LEN(Tel) = 0 OR  Tel = @Tel )
      AND (LEN(Address) = 0 OR  Address = @Address )
      AND (LEN(Email) = 0 OR  Email = @Email )

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