how to set an array as a mysql user variable

Question

I didn't expect to find this so difficult, but I'm trying to set a user variable in MySQL to contain an array of values. I have no clue how to do this so tried doing some research and was quite suprised to find no answer. I have tried:

SET @billable_types = ['client1','client2','client3'];

The reason being I would like to use the variable in the following statement later on:

SELECT sum((time_to_sec(timediff(tlg.time_stop, tlg.time_start))/3600)) as billable_hours
    from mod_tmlog_time_log tlg, mod_tmlog_task_list mttl
    where date(tlg.time_start) >= @time_start
          and date(tlg.time_stop) <= @time_stop
          and mttl.type IN (@billable_types)
            and tlg.task_id = mttl.id
    group by start_date
    order by start_date desc;

Would be very grateful for help.

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Fast forward a while, I ended up with the following quick and dirty solution which doesn't give me the flexibility of re-using the array elsewhere in the code but hey it's an unchargeable admin task so I don't want to spend any more time on it.

SELECT WEEKDAY(tlg.time_start) AS day_of_week, date(tlg.time_start) as start_date,
                            sum((time_to_sec(timediff(tlg.time_stop, tlg.time_start))/3600)) as billable_hours
                    from mod_tmlog_time_log tlg, mod_tmlog_task_list mttl
                    where date(tlg.time_start) >= @time_start
                          and date(tlg.time_stop) <= @time_stop
                          and mttl.type IN ('c1','c2','c3')
                            and tlg.task_id = mttl.id
                    group by start_date
                    order by start_date desc;

joostschouten seems to have found the most elegant solution (not tested it myself yet) but next time I'm writing something which calls for this I will remember to test it!

Answer 1

Just found the answer here: How to cycle with an array in MySQL?

set @billable_types = 'client1,client2,client3';
select * from mttl where find_in_set(mttl.type, @billable_types);