MySql query counting and assigning constants based on ranges - mysql

Question

There's one table
MEMBERS:
id - member id,
dt_activate - member's join unix datetime,
id_inviter - member's id who did invite current member (0 if member joined on his own)
Trying to write a Select that would return the following multiple rows result, where each row would contain:
(1) id - member id;
(2) cnt - count of rows in MEMBERS table where this "id" appeared in id_inviter field and at the same time the dt_activate should be between constants dt_start and dt_end;
(3) img - "imageA.gif" if cnt is between 10-19, "imageB.gif" if between 20-29, "imageC.gif" if greater than 29;
(4) reward - constant X if cnt is between 10-19, Y if between 20-29, Z if greater than 29
Unfortunately my knowledge doesn't let me go past the simple selects like:
SELECT id_inviter, sum(1) AS cnt
FROM members
WHERE dt_activate>=$dt_start AND dt_activate<=$dt_end
GROUP BY id_inviter
HAVING cnt>=10
Estimated record count for MEMBERS table might be between 10-50k.
Please help to achieve the result described above, thank you.

Answer 1

Try this one:
SELECT id_inviter, count (*) AS cnt,
case when count (*) <20 then 'imageA.gif'
when count (*) <30THEN 'imageB.gif' else 'imageC.gif' end as image,
case when count (*) <20 then 'X'
when count (*) <30 THEN 'Y' else 'Z' end as reward
FROM members
WHERE dt_activate>=$dt_start AND dt_activate<=$dt_end
GROUP BY id_inviter
HAVING cnt>=10