create table foo (IDENTITY INT, LoginTime DATETIME);

INSERT INTO foo VALUES( 1, '2019-09-29 17:00:48.000' );
INSERT INTO foo VALUES( 2, '2019-09-29 17:29:02.000' );
INSERT INTO foo VALUES( 3, '2019-09-30 10:22:46.000' );
INSERT INTO foo VALUES( 4, '2019-09-30 11:16:23.000' );

--Select unique
SELECT distinct cast(LoginTime as date) FROM foo GROUP BY LoginTime;