sql脚本获取流水账号的函数

CREATE FUNCTION [dbo].[f_GetGcbh](@Date varchar(100))
RETURNS NVARCHAR(50)
AS
BEGIN
 DECLARE @tempID NVARCHAR(50), @Gcbh NVARCHAR(50)
 SELECT @tempID = max(Gcbh) FROM XmHead WHERE Gcbh LIKE @Date +'%'
 
 IF @tempID IS NULL
  SET @Gcbh = @Date + '01'
 ELSE 
  SET @Gcbh = @Date + RIGHT(('00' + convert(NVARCHAR,(RIGHT(@tempID,2) + 1))),2)
  
 RETURN @Gcbh 
END