DECLARE @startIndex INT,  --用来判断的变量
@ordertype NVARCHAR(500), --条件语句
@SqlBase  NVARCHAR(500)   --最终的sql语句 
SELECT @startIndex=3 
SELECT @ordertype=CASE --根据条件组合sql语句
 WHEN @startIndex=1 THEN  
    'ORDER BY  CM.GeneralID DESC ' 
 WHEN @startIndex=2 THEN 
    'ORDER BY  CM.GeneralID ASC '   
 WHEN @startIndex=3 THEN 
    'ORDER BY  CM.DefaultPicUrl DESC ' 
 END 
 
--拼凑最终的sql语句
SELECT @SqlBase='SELECT TOP 1 GeneralID  FROM PE_CommonModel CM WHERE ISNULL(CM.DefaultPicUrl , '''')!='''' '+'and CM.NodeID IN('''+CAST(34 AS NVARCHAR(10))+''')'+@ordertype
SELECT @SqlBase --查看sql语句
EXEC (@SqlBase) --执行sql语句