create table tb(id varchar(1),riqi datetime)
insert into tb values('A' , '2009-01-22 21:22:22')
insert into tb values('B' , '2009-01-22 19:21:11')
insert into tb values('C' , '2009-01-22 23:10:22')
go
--1
select * from tb where convert(varchar(10),riqi,120) = '2009-01-22'
/*
id riqi
---- ------------------------------------------------------
A 2009-01-22 21:22:22.000
B 2009-01-22 19:21:11.000
C 2009-01-22 23:10:22.000
（所影响的行数为 3 行）
*/
--2
select * from tb where riqi between '2009-01-22 00:00:00' and '2009-01-22 23:59:59'
/*
id riqi
---- ------------------------------------------------------
A 2009-01-22 21:22:22.000
B 2009-01-22 19:21:11.000
C 2009-01-22 23:10:22.000
（所影响的行数为 3 行）
*/
drop table tb
