select/sum of a column with different conditions in 1 query - php

Question

$pos = select * from score_history where content_id = 6 && val = 1
$neg = select * from score_history where content_id = 6 && val = -1
i want to get the pos and neg scores in one query
but i dont want to use join
so perhaps some sort of IF/case statement ?
i've this but as you can guess it fails
SELECT count(*) as total ,
CASE
WHEN `val` = 1 THEN count(*) as `pos`
WHEN `val` = -1 THEN count(*) as `neg`
END
FROM score_history WHERE `content_id` = '46083' ";
is there any way to do this without using join or sub query ?

Answer 1

You can make use of the flexibility of MySQL to handle booleans and integers:
SELECT count(*) total, sum(val = 1) pos, sum(val = -1) neg
FROM score_history
WHERE content_id = '46083';
Whenever the condition is true it is a 1. Otherwise a 0. No CASE needed nor GROUP BY.

Answer 2

Close! A CASE statement doesn't return multiple columns, so you'll need 2 CASE statements and to wrap them in a SUM():
SELECT count(*) as total
,SUM(CASE WHEN `val` = 1 THEN 1 ELSE 0 END) as `pos`
,SUM(CASE WHEN `val` = -1 THEN 1 ELSE 0 END) as `neg`
FROM score_history WHERE `content_id` = '46083' ;

Answer 3

SELECT
SUM(CASE WHEN `val` = 1 THEN 1 ELSE O END) AS pos_count,
SUM(CASE WHEN `val` = -1 THEN 1 ELSE O END) AS neg_count
FROM score_history WHERE `content_id` = '46083';

Answer 4

Try this. Sorry I can't test, no database on this laptop.
select
count(*) as total,
sum(case val when 1 then 1 else 0 end) as pos,
sum(case val when -1 then 1 else 0 end) as neg
from score_history
where content_id = 6

Answer 5

Not sure if this is the best answer (and you would certainly want an index on your val column assuming there are many rows in the table) but this should certainly work - also assuming you only have 1 and -1 as values:
SELECT count(*), val from score_history where content_id = 6 group by val;

Answer 6

You were close; try the SUM function:
SELECT count(*) as total
, sum(CASE WHEN `val` = 1 THEN 1 ELSE 0 END) as `pos`
, sum(CASE WHEN `val` = -1 THEN 1 ELSE 0 END) as `neg`
FROM score_history
WHERE `content_id` = '46083';

Answer 7

select count(*)
from score_history
where content_id = 6 &&
(val = -1 or val=1)
group by val
I think this statement should work but I have tested on DBMS.

Answer 8

SELECT count(*) as total ,
count(case when val = 1 then 1 else null end) as pos,
count(case when val = -1 then 1 else null end) as neg
FROM score_history
WHERE `content_id` = '46083';
See SQLFIDDLE

Answer 9

Okay, a lot of these answers are close, but whenever you use an aggregate function you should use a group by.
SELECT count(*) as total
, (CASE WHEN `val` >= 0 THEN 'positive' ELSE 'negative' END) as interpreted_value
END
FROM score_history
WHERE `content_id` = '46083'
GROUP BY (CASE WHEN `val` >= 0 THEN 'positive' ELSE 'negative' END);
If you want to read up on how to use group by and aggregate functions here: https://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html