MySQL only return user from tableA if no specific value status in tableB?

Question

I have a table of user (table users) and a log table (table logs) with serval logs about the user. Now I'm looking for a way to return me a list of user where a specific value in the logs is missing.

Lets have the following example:

  table users        table logs
----------------   -----------------------------
| id | user    |   | id | user_id | status     |
----------------   -----------------------------
|  1 | user1   |   |  1 |       2 | send       |
----------------   -----------------------------
|  2 | user2   |   |  2 |       1 | send-error |
----------------   -----------------------------
|  3 | user3   |   |  3 |       3 | status-x   |
----------------   -----------------------------
                   |  4 |       1 | send       |
                   -----------------------------
                   |  5 |       3 | send-error |
                   -----------------------------

The following join returns me a list of all users and there logs:

SELECT u.id, u.name, l.status
FROM users u
LEFT JOIN logs l ON u.id = t.user_id

How can I select only the ones which have not the status 'send'? In this example it should just return id=3, user=user3 .

Answer 1

SELECT u.id, u.name, l.status
FROM   users u
LEFT JOIN logs l ON u.id = l.user_id
WHERE  NOT EXISTS (SELECT 1 FROM logs g
                   WHERE  u.id = g.user_id
                   AND    g.status = 'send')

Basically, check out NOT EXISTS for queries like the one you want. If the subquery would return no rows, the NOT EXISTS condition holds, and the row is returned.

Edit:

If you only wish to see which users do not have a status of "send" in the logs table:

SELECT u.id, u.name
FROM   users u
WHERE  NOT EXISTS (SELECT 1 FROM logs l
                   WHERE  u.id = l.user_id
                   AND    l.status = 'send')

This query avoids the need for GROUP BY just to get one user per row, if that is all you are trying to do.

Answer 2

SELECT u.id, u.user, l.status
FROM users u
LEFT JOIN logs l ON u.id = l.user_id
WHERE l.status not like '%send%'

You are already performing the left join (assuming that you want all users and those log entries where the user ID matches). It's a simple matter then to check the status field for the absence of the word 'send'.