Question

I have two tables in a database. Table1 stores the users and Table2 stores data generated by the users.

Due to an error some users from Table1, don’t have any data in Table2. I would like to notify these users.

I am trying this in several ways using MySQL. But nothing works, because PHPmyAdmin freezes or PHP times out. That’s maybe because the first table contains 28.000 rows and the second one contains 80.000 rows. I just need the last 5 days.

Trial nr 1

SELECT gebruikers.g_id
FROM gebruikers LEFT JOIN objecten ON objecten.o_g_id=gebruikers.g_id
WHERE objecten.o_g_id IS NULL

EXPLAIN SELECT

id  select_type     table   type    possible_keys   key     key_len     ref     rows    Extra
1   SIMPLE  gebruikers  index   NULL    PRIMARY     4   NULL    25227   Using index
1   SIMPLE  objecten    ALL     NULL    NULL    NULL    NULL    81002   Using where; Not ex

Trial nr 2

SELECT g_id FROM gebruikers
WHERE g_id NOT IN(SELECT o_g_id FROM objecten WHERE o_startdatum <= NOW() AND o_startdatum >=NOW() - INTERVAL 5 DAY)

What am i doing wrong?

Answer 1

Query to get required records:

SELECT 
    gebruikers.g_id
FROM
    gebruikers
        LEFT JOIN
    objecten ON objecten.o_g_id = gebruikers.g_id
WHERE
    objecten.o_g_id IS NULL
        and o_startdatum <= NOW()
        AND o_startdatum >= (NOW() - INTERVAL 5 DAY);