Adding a where to a nested query in Laravel - php

Question

I want some help with a WHERE clause $start date is set further up in the code, and the query works when running against SQL from within Laravel. I get an error saying that $startdate isn't set. I am not sure that I am even doing WHERE correctly.
$query = DB::query()
->select('CC AS CountOfVisits', DB::raw('count(CC) AS Users'))
->fromSub
(function (\Illuminate\Database\Query\Builder $query) {
$query->select('user_id', DB::raw('count(user_id) AS CC '))
->from('mytable')
->where('created_at', '>=', $startdate)
->groupBy('user_id');
}, 'CC')
->groupBy('CC');
$result = DB::connection('mysql2')->select($query->toSql());

Answer 1

I'm putting this here for others who find this page. It should be noted that fromSub() can also take a Builder object instead of a closure.
$builder = DB::table('mytable')->where('created_at', '>=', $start_date)
->select('user_id', DB::raw('count(user_id) AS CC '))
->groupBy('user_id');
$query = DB::query()
->select('CC AS CountOfVisits', DB::raw('count(CC) AS Users'))
->fromSub($builder, 'temp')
->groupBy('CC');
In my case, I already had a Builder object that I wanted to use in a sub select.

Answer 2

That's because your fromSub is an anonymous function, also known as a closures. It does not know about variables that you define outside of the closure. You can read more about them in the official PHP docs
Rewrite your query to:
$result = DB::connection('mysql2')
->query()
->select('CC AS CountOfVisits', DB::raw('count(CC) AS Users'))
->fromSub(function($query) use ($startdate) {
$query->select('user_id', DB::raw('count(user_id) AS CC '))
->from('mytable')
->where('created_at','>=',$startdate)
->groupBy('user_id');
}, 'temp')
->groupBy('CC')
->get();