Question

我想在sql server的情况下创建多个if else语句。是否有可能请给我一个例子。在c＃中，您可以在案例中编写多行语句。

是否可以在SQL Server中使用C＃switch case。

我想将以下代码放在case loop

中

IF @SegmentId > 0 and @AttributeName IS NOT NULL   
begin
  select AttributeID,Attribute_key from AttributeMaster 
  where AttributeTypeId =@AttributeType and SegmentId=@SegmentId 
  and Attribute_key   like '%'+@AttributeName+'%' order by AttributeID
end

else IF @SegmentId = 0 and NULLIF(@AttributeName, '') IS NULL   
begin
  select AttributeID,Attribute_key from AttributeMaster 
  where AttributeTypeId =@AttributeType  order by AttributeID
end

else IF @SegmentId > 0 and NULLIF(@AttributeName, '') IS NULL   
begin
  select AttributeID,Attribute_key from AttributeMaster 
  where AttributeTypeId =@AttributeType and SegmentId=@SegmentId  
  order by AttributeID
end

我需要实现@AttributeTypeId是1然后不同的条件。来自my@AttributeId

的1 to 5

Answer 1

如果您正在寻找Tsql CASE以及它如何运作;

--(1) Simple case
case X when 1 then 'X is 1' 
       when 2 then 'X is 2' ...
       else 'X is not 1 or 2' end as colName

--(2) Searched case
case when X < 1 then 'X is less than 1' 
     when X = 1 then 'X is 1' ...
     else 'X is greater than 1' end as colName

我认为你的整个事情可以放在into a single query;

select AttributeID, Attribute_key 
       --uncomment next line if needed   
       --,case AttributeID when 1 then 'A' when 2 then 'B' ... end 
from  AttributeMaster
where AttributeTypeId =@AttributeType and 
      SegmentId= isnull(nullif(@SegmentId,0),SegmentId) and
      Attribute_key like 
           case when  @SegmentId > 0 and @AttributeName is not null 
           then '%'+@AttributeName+'%' else Attribute_key end
      --uncomment if filter needed
      --and AttributeID <6

Answer 2

您可以使用下面的SQL查询

执行问题中提到的所有if / else条件

select AttributeID,Attribute_key from AttributeMaster 
where AttributeTypeId =@AttributeType 
and (@segmentId = 0 or SegmentId=@SegmentId)
and (NULLIF(@AttributeName, '') IS NULL OR 
         Attribute_key   like '%'+@AttributeName+'%') 
order by AttributeID

如何在SQL Server的Case语句中执行Multiple If语句

2 个答案: