Question

I have query that use variables when I try run it on navicat it works well. but in some reason I have issues run it on Yii.

I use this code:

$connection = Yii::app()->db;
$sql = "
select  s.name, s.type
from    (
        select  *
        ,       (@rn := if(@cur=type, @rn+1, 1)) as rn
        ,       @cur := type
        from    games
        join    (select @cur := '') i
        order by
                type
        ) s
where   rn <= 10 ";

$command = $connection->createCommand($sql);
$results = $command->queryAll();

this query should select 10 games names from each game type. that what happens when I run it on navicat, when I try it in the site it return me only one game name for each game type.
anyone know the reason why it happens? how to fix it? maybe how run it with criteria? please help me.

btw The reason I use this query (tnx to Andomar) is because other queries take up a lot of resources.

Answer 1

It’s not a Yii problem. Using pure PDO, this sql returns only one row.
Analizing the subquery results, I realized that the @rn variable didn’t store the previous value, but @cur did. So, I added the join to initialize the @rn variable.

Change your SQL to:

$connection = Yii::app()->db;
$sql = "
select  s.name, s.type
from    (
        select  *
        ,       (@rn := if(@cur=type, @rn+1, 1)) as rn
        ,       @cur := type
        from    games
        join    (select @cur := '') i
        join    (select @rn := '') j
        order by
                type
        ) s
where   rn <= 10 ";

$command = $connection->createCommand($sql);
$results = $command->queryAll();