解析PageID的UDF

CREATE FUNCTION [dbo].udf_GetPage(@page_num BINARY(6))
RETURNS VARCHAR(11)
AS
BEGIN
RETURN(CONVERT(VARCHAR(2),(CONVERT(INT,SUBSTRING(@page_num,6,1))*POWER(2,8))+
(CONVERT(INT,SUBSTRING(@page_num,5,1))))+':'+
CONVERT(VARCHAR(11),
(CONVERT(INT,SUBSTRING(@page_num,4,1))*POWER(2,24))+
(CONVERT(INT,SUBSTRING(@page_num,3,1))*POWER(2,16))+
(CONVERT(INT,SUBSTRING(@page_num,2,1))*POWER(2,8))+
(CONVERT(INT,SUBSTRING(@page_num,1,1)))))
END