Question

I have two tables

user table

 user_id | name  |
    1    | peter |
    2    | kofi  |
    3    | sam   |
    4    | nasah |
    5    | sarah |
    6    | david |
    7    | dan   |

time table

 time_id | user_id | register
    1    |     1   |  present
    2    |     2   |  absent
    3    |     3   |  absent
    4    |     4   |  present
    5    |     5   |  absent

in the “time” table under “register” column, user can iether register “present” or “absent” when they login into the system.

I want a mysql query that select users who have either register “absent” or has not register at all.

the return result should be

kofi  | absent
sam   | absent
sarah | absent
david | 
dan   | 

Answer 1

What about this

SELECT t2.name, t1.register 
FROM time t1
RIGHT JOIN user t2
ON t2.user_id=t1.user_id
WHERE (t1.register = 'absent' OR t1.register is null)

Its working, tested here.

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Update 1

Per you conversation, you want to further filter based on time/ date

let say i want to find out those who where absent or did not enter the system before 06-13-12 assuming there is a column name “date” in the time table

Use below query

SELECT t2.name, t1.register, t1.mydate 
FROM time t1
RIGHT JOIN user t2
ON t2.user_id=t1.user_id
WHERE 
     (t1.register = 'absent' OR t1.register is null)
     AND
     (t1.mydate <= '2012-06-13' OR t1.mydate is null)

Here is demo for new requirement

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Hope this is what you wanted.