Drop table if exists my_users;
Create table my_users
(User_ID serial primary key
,Name varchar(100) not null unique
);
Insert into my_users values
(1,'John'),
(2,'Peter'),
(3,'Anne'),
(4,'May');
Drop table if exists my_ATTENDANCE;
Create table my_attendance
(user_ID INT NOT NULL
,Date date not null
,primary key(user_id,date)
);
Insert into my_attendance values
( 2 ,'2019-02-16'),
( 2 ,'2019-02-17'),
(2 ,'2019-02-18'),
(3 ,'2019-02-17'),
(4 ,'2019-02-18');
Select u.*
From my_users u
Left
Join my_attendance a
On a.user_id = u.user_id
and a.date = '2019-02-18'
Where a.user_id is null;
User_ID Name
3 Anne
1 John
https://rextester.com/YQZTM12580