withCount() - get difference of 2 counts - mysql

Question

I have a table that has a column is_up_vote = true|false
I am trying to write a query using withCount() so it returns me the sum of true values and false values.
select COUNT(is_up_vote) from comment_votes WHERE is_up_vote = true returns 17
select COUNT(is_up_vote) from comment_votes WHERE is_up_vote = false returns 15
However I couldn't figure out how to get different of them, so the total returns 2.
What I tried is:
Model::withCount(['votes' => function($q) {
$q->selectRaw(
'(SUM (COUNT(is_up_vote) WHERE is_up_vote = true) - (COUNT(is_up_vote) WHERE is_up_vote = false) )'
);
}]);
But this returns 17+15 = 32
without SUM(), it's also returning 32.
$q->selectRaw(
'( (COUNT(is_up_vote) WHERE is_up_vote = true) - (COUNT(is_up_vote) WHERE is_up_vote = false) )'
);
What am I doing wrong?
Edit:
If I try one side, it ignores the where and still returns 32, so the where is not getting called (where it does in sql)
return $query->withCount(['votes' => function($q) {
$q->selectRaw('(COUNT(is_up_vote) WHERE is_up_vote = true)');
}]);
maunal sequel query returns 17:
select COUNT(is_up_vote) from comment_votes WHERE is_up_vote = true
Edit 2:
$query->withCount([
'votes as up_votes_count' => function($q) {
$q->where('is_up_vote', true);
},
'votes as down_votes_count' => function($q) {
$q->where('is_up_vote', false);
},
]);
The only thing that I could make work is this, but it'd need extra step for getting the total, so I didn't really like this approach. I'm sure someone more proficient with queries can come up with something with direct query.

Answer 1

withCount may not be able to handle this case. what about using addSelect to calculate the votes count.
return Model::addSelect(['votes_count' => Vote::selectRaw('( (COUNT(is_up_vote) WHERE is_up_vote = true) - (COUNT(is_up_vote) WHERE is_up_vote = false) )')
->whereColumn('parent_id', 'parents.id')
])->get();
I don't know whether the sub-query is gonna work. But you know the idea.

Answer 2

According to the instructions commented by #Jefferson Pessanha, just using Model::selectRaw('(abs(2 * sum(is_up_vote) - count(*)))')->get(); would be enough

Answer 3

create table comment_votes
(
is_up_vote tinyint(1) default 1 null
);
insert into comment_votes values (true),(true),(true),(true),(true),(true),(true),(true),(true),(true),(true),(true),(true),(true),(true),(true),(true);
insert into comment_votes values (false),(false),(false),(false),(false),(false),(false),(false),(false),(false),(false),(false),(false),(false),(false);
select COUNT(is_up_vote) from comment_votes WHERE is_up_vote = true;
returns 17
select COUNT(is_up_vote) from comment_votes WHERE is_up_vote = false;
returns 15
select (abs(2 * sum(is_up_vote) - count(*))) from comment_votes;
returns 2
Explain:
trueValues + falseValues = total
falseValues = total - trueValues
trueValues - falseValues = x
trueValues - (total - trueValues) = x
2 * trueValues - total = x
trueValues = sum(is_up_vote) [only trues stored as 1 are counted]
total = count(*)
Abs function is to convert the result to positive in case of negative
Isn't it correct?

Answer 4

Try this.
select
sum( if(is_up_vote= true, 1, 0) ) as uptrue,
sum( if(is_up_vote= false, 1, 0) ) as upfalse,
sum( if(is_up_vote= true, 1, -1) ) as updiff
from comment_votes
Edit: 1
Instead of checking if it is true or false, try this.
select
sum( if(is_up_vote, 1, 0) ) as uptrue,
sum( if(is_up_vote, 0, 1) ) as upfalse,
sum( if(is_up_vote, 1, -1) ) as updiff
from comment_votes