T-SQL自定义函数：从身份证提取信息

CREATE   FUNCTION  dbo.GetInfoFromIDCard
(
   @IDCard   VARCHAR ( 18 ),
   @InfoType   VARCHAR ( 20 )
)
RETURNS   NVARCHAR ( 20 )
AS  
BEGIN
       DECLARE   @Ret   NVARCHAR ( 20 )
       SELECT
             @Ret   =   CASE   @InfoType
                     -- TODO:根据身份证1~6位判断出户籍所在地
                     -- WHEN 'Region' THEN
                      WHEN   ' Birthday '
                      THEN   CASE   LEN ( LTRIM ( RTRIM ( @IDCard )))
                             -- 如果身份证为15位
                             -- 身份证7~12代表出生日期19XX-XX-XX
                             WHEN   15
                             THEN   ' 19 '   +   SUBSTRING ( @IDCard ,  7 ,  2 )
                                  +   ' - '   +   RIGHT ( ' 00 '   +   SUBSTRING ( @IDCard ,  9 ,  2 ),  2 )
                                  +   ' - '   +   RIGHT ( ' 00 '   +   SUBSTRING ( @IDCard ,  11 ,  2 ),  2 )
                             -- 如果身份证为18位
                             -- 身份证7~14代表出生日期XXXX-XX-XX
                             WHEN   18
                             THEN
                                  SUBSTRING ( @IDCard ,  7 ,  4 )
                                  +   ' - '   +   RIGHT ( ' 00 '   +   SUBSTRING ( @IDCard ,  11 ,  2 ),  2 )
                                  +   ' - '   +   RIGHT ( ' 00 '   +   SUBSTRING ( @IDCard ,  13 ,  2 ),  2 )
                             ELSE   NULL
                           END
                      WHEN   ' Gender '
                      THEN   CASE   LEN ( LTRIM ( RTRIM ( @IDCard )))
                             -- 如果身份证为15位
                             -- 倒数第一位数为奇数则为男,偶数则为女
                             WHEN   15
                             THEN   CASE   CAST ( RIGHT ( @IDCard ,  1 )  AS   INT )
                                    %   2
                                    WHEN   1   THEN  N ' M '
                                    ELSE  N ' F '
                                  END
                             -- 如果身份证为18位
                             -- 倒数第二位数为奇数则为男,偶数则为女
                             WHEN   18   THEN
                                  CASE   CAST ( LEFT ( RIGHT ( @IDCard ,  2 ),  1 )  AS   INT )
                                    %   2
                                    WHEN   1   THEN  N ' M '
                                    ELSE  N ' F '
                                  END
                             ELSE   NULL
                           END
                    END
       WHERE
             -- 判断身份证7~14位的数字是否为日期类型
             ISDATE ( CASE   LEN ( LTRIM ( RTRIM ( @IDCard )))
                      WHEN   15
                      THEN   ' 19 '   +   SUBSTRING ( @IDCard ,  7 ,  2 )
                           +   ' - '   +   RIGHT ( ' 00 '
                                         +   SUBSTRING ( @IDCard ,  9 ,  2 ),
                                         2 )  +   ' - '
                           +   RIGHT ( ' 00 '   +   SUBSTRING ( @IDCard ,  11 ,  2 ),
                                   2 )
                      WHEN   18
                      THEN   SUBSTRING ( @IDCard ,  7 ,  4 )  +   ' - '
                           +   RIGHT ( ' 00 '   +   SUBSTRING ( @IDCard ,  11 ,  2 ),
                                   2 )  +   ' - '   +   RIGHT ( ' 00 '   +   SUBSTRING ( @IDCard ,  13 ,  2 ),  2 )
                    END )  =   1
             -- 判断身份证位数是15位或者18位
             AND  (
             LEN ( LTRIM ( RTRIM ( @IDCard )))  =   15
             OR   LEN ( LTRIM ( RTRIM ( @IDCard )))  =   18
            )
       RETURN   @Ret
END