create table tb(id int,date datetime)
insert tb(id) values(1)
insert tb values(2,'2007-10-01')
insert tb(id) values(3)select * from tb where date is not nullselect * from tb where date is nulldrop table tb/*
id date
----------- ------------------------------------------------------
2 2007-10-01 00:00:00.000(所影响的行数为 1 行)id date
----------- ------------------------------------------------------
1 NULL
3 NULL(所影响的行数为 2 行)
*/
insert tb(id) values(1)
insert tb values(2,'2007-10-01')
insert tb(id) values(3)select * from tb where date is not nullselect * from tb where date is nulldrop table tb/*
id date
----------- ------------------------------------------------------
2 2007-10-01 00:00:00.000(所影响的行数为 1 行)id date
----------- ------------------------------------------------------
1 NULL
3 NULL(所影响的行数为 2 行)
*/
insert tb(id) values(1)
insert tb values(2,'2007-10-01')
insert tb(id) values(3)select id,date=isnull(date,getdate()) from tbdrop table tb/*
id date
----------- ------------------------------------------------------
1 2007-12-29 12:47:23.833
2 2007-10-01 00:00:00.000
3 2007-12-29 12:47:23.833(所影响的行数为 3 行)
*/
insert tb(id) values(1)
insert tb values(2,'2007-10-01')
insert tb(id) values(3)select id, date=isnull(date, getdate()) from tb /*
id date
----------- -----------------------
1 2007-12-29 12:40:43.177
2 2007-10-01 00:00:00.000
3 2007-12-29 12:40:43.177(3 row(s) affected)
*/drop table tb
insert tb(id) values(1)
insert tb values(2,'2007-10-01')
insert tb(id) values(3)select case when [date] is null then getdate() else [date] end as [date]
from tb/*
date
------------------------------------------------------
2007-12-29 12:42:45.493
2007-10-01 00:00:00.000
2007-12-29 12:42:45.493(所影响的行数为 3 行)
*/
drop table tb
select isnull(LocalTime,getdate())[LocalTime] from 表名
--or
select case when LocalTime is null then getdate() else LocalTime end [LocalTime] from 表名