How to create a join that uses a subquery? - cakephp

Question

How do you convert the following SQL Query to a CakePhp Find Query?
SELECT
a.id, a.rev, a.contents
FROM
YourTable a
INNER JOIN (
SELECT
id, MAX(rev) rev
FROM
YourTable
GROUP BY
id
) b ON a.id = b.id AND a.rev = b.rev
I have tried the code below:
return $model->find('all', [
'fields' => $fields,
'joins' => [
[
'table' => $model->useTable,
'fields' => ['id','MAX(rev) as rev'],
'alias' => 'max_rev_table',
'type' => 'INNER',
'group' => ['id'],
'conditions' => [
$model->name.'.id= max_rev_table.id',
$model->name.'.rev = max_rev_table.rev'
]
]
],
'conditions' => [
$model->name.'.emp_id' => $empId
]
]);
But it seems that in the generated SQL, the fields under the joins is not included. So I don't get the max(rev) which I need to get only the rows with max(rev).
I have tried rearranging the items inside joins but still produces same auto-generated SQL.
Can you please help me?

Answer 1

There are no fields or group options for joins, the only options are table, alias, type, and conditions.
If you want to join a subquery, then you need to explicitly generate one:
$ds = $model->getDataSource();
$subquery = $ds->buildStatement(
array(
'fields' => array('MaxRev.id', 'MAX(rev) as rev'),
'table' => $ds->fullTableName($model),
'alias' => 'MaxRev',
'group' => array('MaxRev.id')
),
$model
);
and pass it to the joins table option:
'table' => "($subquery)"
See also
Cookbook > Models > Associations: Linking Models Together > Joining tables
Cookbook > Models > Retrieving Your Data > Sub-queries