Question

I have MySQL table with structure:

| uid     |   itemid
| -------------------
| 1001    |   9999
| 1001    |   8888
| 2002    |   8888
| ...     |   ...

uid and itemid not unique columns. Bun uid+itemid is unique combination.

I need count rows by itemid. I use next query:

SELECT itemid, COUNT(*) 
FROM unlikes 
WHERE itemid IN ('9999', '8888') GROUP BY itemid;

And this works!

Next, i need to know which row have concrete uid. I use:

SELECT itemid, COUNT(*), IF (uid = '1001', TRUE, FALSE) toggled 
FROM unlikes 
WHERE itemid IN ('9999', '8888') GROUP BY itemid;'

Not work. If i have more than one row with itemid = 8888, than toggled = FALSE. I need toggled = TRUE if one in group have uid = 1001;

Answer 1

SELECT itemid, COUNT(*), 
CASE WHEN uid = 1001 THEN TRUE ELSE FALSE end AS toggled 
FROM unlikes 
WHERE itemid IN ('9999', '8888') GROUP BY itemid;