游标的一个简单应用,做一个简单的笔记。
作用:计算当前时刻与最大时刻的差值,并跟新差值minusTime列。
create table TimeManage
(
ID int,
breakfast datetime,
minusTime int
)
insert into TimeManage(ID,breakfast) values(1,'2017-10-10 10:12:10')
insert into TimeManage(ID,breakfast) values(1,'2017-10-10 10:18:10')
insert into TimeManage(ID,breakfast) values(2,'2017-10-10 10:10:10')
insert into TimeManage(ID,breakfast) values(3,'2017-10-10 10:19:10')
insert into TimeManage(ID,breakfast) values(1,'2017-10-10 10:20:10')
insert into TimeManage(ID,breakfast) values(1,'2017-10-10 10:30:10')
insert into TimeManage(ID,breakfast) values(2,'2017-10-10 11:10:10')
insert into TimeManage(ID,breakfast) values(3,'2017-10-10 12:19:10')
select * from TimeManage
DECLARE
@ID int
DECLARE YOUCURNAME CURSOR FOR select distinct ID from TimeManage
OPEN YOUCURNAME
fetch next from YOUCURNAME into @ID
while @@fetch_status=0
begin
--您要执行的操作写在这里
declare @times datetime
select @times=MAX(breakfast) from [dbo].[TimeManage] where ID = @ID
update TimeManage set minusTime=DATEDIFF ( second , breakfast, @times ) where ID = @ID
fetch next from YOUCURNAME into @ID
end
close youcurname
deallocate youcurname
结果: