MySQL GROUP BY column ignorning specific value - mysql

Question

I have a query on a table of phone calls that uses GROUP BY to show only unique caller ids. The problem is that if a caller has caller id blocking their caller id shows up as "Unknown" and the client doesn't want all Unknowns to be summed up together. So basically, instead of just GROUP BY caller_id I need to somehow do something like GROUP BY caller_id IF caller_id != 'Unknown'
Is this even possible? I'd like to avoid doing all the group processing in PHP if at all possible.

Answer 1

You can do something like:
SELECT caller_id FROM phone_calls WHERE caller_id != 'Unknown' GROUP BY caller_id;
or consider DISTINCT - in most cases it is faster - if you have index created on caller_id the performance is usually the same, but if not DISTINCT is better. If you need :
... show only unique caller ids ..
but maybe for your case (doing aggregation or something similar) you are not able to use it but just in case:
SELECT DISTINCT caller_id FROM phone_calls WHERE caller_id != 'Unknown';
-- EDIT AFTER discussion in comments
SELECT * FROM callers;
+----+-----------+-----------+
| id | caller_id | call_time |
+----+-----------+-----------+
| 1 | abc | 24 |
| 2 | abc | 16 |
| 3 | xyz | 10 |
| 4 | xyz | 10 |
| 5 | Unknown | 11 |
| 6 | Unknown | 12 |
| 7 | Unknown | 13 |
| 8 | xyz | 1 |
| 9 | abc | 10 |
+----+-----------+-----------+
SELECT caller_id, SUM(call_time) FROM callers
WHERE caller_id != 'Unknown'
GROUP BY caller_id;
+-----------+----------------+
| caller_id | SUM(call_time) |
+-----------+----------------+
| abc | 50 |
| xyz | 21 |
+-----------+----------------+
SELECT caller_id, SUM(call_time) FROM callers
GROUP BY caller_id;
+-----------+----------------+
| caller_id | SUM(call_time) |
+-----------+----------------+
| abc | 50 |
| Unknown | 36 |
| xyz | 21 |
+-----------+----------------+
SELECT caller_id, SUM(call_time) as total_time FROM callers
WHERE caller_id != 'Unknown'
GROUP BY caller_id
UNION
SELECT caller_id, call_time FROM callers
WHERE caller_id = 'Unknown';
+-----------+------------+
| caller_id | total_time |
+-----------+------------+
| abc | 50 |
| xyz | 21 |
| Unknown | 11 |
| Unknown | 12 |
| Unknown | 13 |
+-----------+------------+
SELECT caller_id, SUM(call_time) as total_time FROM callers
GROUP BY caller_id,
(case when caller_id = 'Unknown'
AND id is not null
then id end
);
+-----------+------------+
| caller_id | total_time |
+-----------+------------+
| abc | 50 |
| Unknown | 11 |
| Unknown | 12 |
| Unknown | 13 |
| xyz | 21 |
+-----------+------------+