Write custom SQL query for multiple counts

问题

I have the table in MySQL, containing group_name and username, like this:

ID|group_name|username
----------------------
1 |    A     | user1
----------------------
2 |    B     | user2
----------------------
3 |    C     | user1

...

And I have some logical expression that looks like this:

(A & B) || C

Which means, that if I'm searching by some user, this user should be in both groups A and B, or in C.

I have to check users with custom expressions in Laravel, and my query will look like this:

return DB::table('assigned_groups')->where($expression)->where('username', $username)->count();

Where $expression is my logical expression written in raw SQL, I guess. And I have to check whether some $username can be found assigned to needed groups at least once.

For now I just have a piece of pseudocode for $expression like this:

select count(*)
having (
    (count(select(*) where group_name = A) > 0 
    and count(select(*) where group_name = B) > 0)
    or count(select(*) where group_name = C) > 0
)

How do I write this expression correctly? How should I change my Laravel query and $expression itself?

UPD: now my SQL looks like this, and it's almost something

SELECT count(*) FROM `assigned_groups`
where username = 'user1'
having (
    (count(case group_name when 'A' then 1 else null end) > 0 
    and count(case group_name when 'B' then 1 else null end) > 0)
    or count(case group_name when 'C' then 1 else null end) > 0
)

回答1:

You can write your raw expression using havingRaw

DB::table('assigned_groups')
->where('username', $username)
->havingRaw("(count(case group_name when 'A' then 1 else null end) > 0 
    and count(case group_name when 'B' then 1 else null end) > 0)
    or count(case group_name when 'C' then 1 else null end) > 0")
->count();

or shorter using sum()

DB::table('assigned_groups')
->where('username', $username)
->havingRaw("(sum(group_name ='A') > 0 and sum(group_name = 'B') > 0) or sum(group_name = 'C') > 0")
->count();

回答2:

Try this:

return DB::table('assigned_groups')
    ->where('username', $username)
    ->andWhere(function($query) use ($groupAandB, $groupC) {
        $query->whereIn('group_name', $groupAandB)
              ->orWhereIn('group_name', $groupC);
    })
    ->count();

I actually am not sure if there's an orWhereIn method, but this structure should give you a good starting point.

回答3:

try this one :

$users = DB::select("select count() from user where username='$username' and (username in (select username from user where group_name in ('A','B') having count() >1 group by username) or group_name ='C')");

来源：https://stackoverflow.com/questions/50331835/write-custom-sql-query-for-multiple-counts