一个表的记录之间的日期间隔如何取，太难了,请求SQL高手支援！_Sql Server

一个表的记录之间的日期间隔怎么取，太难了,请求SQL高手支援！！！
有以下表结构(tablename)

ID UserID thedate thetime(单位：分钟)
-------------------------------
1 AL000984 1899-12-30 10:41:00
5 AL000984 1899-12-30 10:42:00
6 AL000984 1899-12-30 10:46:00
14 AL000984 1899-12-30 10:57:00

17 BL000985 1899-12-30 11:06:00
18 BL000985 1899-12-30 11:14:00
44 BL000985 1899-12-30 11:24:00
50 BL000985 1899-12-30 11:36:00
51 BL000985 1899-12-30 11:46:00

tablename中有多个用户（现在示例中仅列出两个用户AL000984和BL000985），thedate字段是一个日期时间字段，是某业务操作时间，有先后顺序，现在我想
根据用户来取得相邻两记录相差的时间值，并写入thetime字段内,单位为分钟,
即要得下面的结果：

ID UserID thedate thetime(单位：分钟)
-------------------------------
1 AL000984 1899-12-30 10:41:00 0
5 AL000984 1899-12-30 10:42:00 1
6 AL000984 1899-12-30 10:46:00 4
14 AL000984 1899-12-30 10:57:00 11

17 BL000985 1899-12-30 11:06:00 0
18 BL000985 1899-12-30 11:14:00 8
44 BL000985 1899-12-30 11:24:00 10
50 BL000985 1899-12-30 11:36:00 12
51 BL000985 1899-12-30 11:46:00 10

希望用一条SQL语句解决，谢谢大侠门！本人对在一个表中进行不同记录之间的比较很少做，不知从何下手

------解决方案--------------------

SQL code

create table tb(ID int,UserID varchar(10),thedate varchar(10),thetime varchar(10))insert into tb values(1  ,'AL000984', '1899-12-30', '10:41:00') insert into tb values(5  ,'AL000984', '1899-12-30', '10:42:00') insert into tb values(6  ,'AL000984', '1899-12-30', '10:46:00') insert into tb values(14 ,'AL000984', '1899-12-30', '10:57:00') insert into tb values(17 ,'BL000985', '1899-12-30', '11:06:00') insert into tb values(18 ,'BL000985', '1899-12-30', '11:14:00') insert into tb values(44 ,'BL000985', '1899-12-30', '11:24:00') insert into tb values(50 ,'BL000985', '1899-12-30', '11:36:00') insert into tb values(51 ,'BL000985', '1899-12-30', '11:46:00') goselect t.id,t.UserID,t.thedate,t.thetime,[minute] = 0 from(  select px=(select count(1) from tb where UserID=a.UserID and cast(thedate + ' ' + thetime as datetime)<cast(a.thedate + ' ' + a.thetime as datetime))+1 , * from tb a) t where px = 1union allselect n.id,n.UserID,n.thedate,n.thetime,[minute]=datediff(minute,cast(m.thedate + ' ' + m.thetime as datetime),cast(n.thedate + ' ' + n.thetime as datetime)) from(  select px=(select count(1) from tb where UserID=a.UserID and cast(thedate + ' ' + thetime as datetime)<cast(a.thedate + ' ' + a.thetime as datetime))+1 , * from tb a) m,(  select px=(select count(1) from tb where UserID=a.UserID and cast(thedate + ' ' + thetime as datetime)<cast(a.thedate + ' ' + a.thetime as datetime))+1 , * from tb a) nwhere m.UserID = n.UserID and m.px = n.px - 1 order by t.userid,t.thedate,t.thetimedrop table tb/*id          UserID     thedate    thetime    minute      ----------- ---------- ---------- ---------- ----------- 1           AL000984   1899-12-30 10:41:00   05           AL000984   1899-12-30 10:42:00   16           AL000984   1899-12-30 10:46:00   414          AL000984   1899-12-30 10:57:00   1117          BL000985   1899-12-30 11:06:00   018          BL000985   1899-12-30 11:14:00   844          BL000985   1899-12-30 11:24:00   1050          BL000985   1899-12-30 11:36:00   1251          BL000985   1899-12-30 11:46:00   10*/
------解决方案--------------------
SQL codecreate table tb(ID int,UserID varchar(10),thedate datetime,thetimes int)insert into tb(id,UserID,thedate) values(1  ,'AL000984', '1899-12-30 10:41:00') insert into tb(id,UserID,thedate) values(5  ,'AL000984', '1899-12-30 10:42:00') insert into tb(id,UserID,thedate) values(6  ,'AL000984', '1899-12-30 10:46:00')(
------解决方案--------------------
SQL code 
 declare @t table (ID int,UserID varchar(10),thedate varchar(10),thetime varchar(10))