Laravel query in if cause - laravel

Question

I run the below query, if cause true then where cause is apply like below, but when i run below query it gives me "Out of memory (allocated 503316480) (tried to allocate 492834816 bytes)" error, So another easy way to check the where cause above if condition.
Here below is my code.
$user_id = "";
$doctor_id = "";
$start_date = "";
$end_date = "";
if(isset($request->user_id)) {
$user_id = $request->user_id;
}
if(isset($request->doctor_id)) {
$doctor_id = $request->doctor_id;
}
if(isset($request->start_date)) {
$start_date = $request->start_date;
}
if(isset($request->end_date)) {
$end_date = $request->end_date;
}
$query = DB::table('request_approves')
->join('city_masters', 'request_approves.city_id', '=', 'city_masters.id')
->join('doctors', 'request_approves.doctor_id', '=', 'doctors.id')
->select('doctors.*','city_masters.*','request_approves.*');
if($user_id !== "") {
$query->where('request_approves.user_id', 2);
}
if($doctor_id !== "") {
$query->where('request_approves.doctor_id',3);
}
if($start_date !== "" & $end_date !==""){
$query->whereBetween('request_approves.approve_time', array($start_date,$end_date));
}
$query->get();

Answer 1

Not sure what it is happening, but your code seems wrong to me .
On the if statements you do something like this $query->where('request_approves.user_id', 2); but where this returned values go ? To continue the same query you should do it like this:
$query = DB::table('request_approves')
->join('city_masters', 'request_approves.city_id', '=', 'city_masters.id')
->join('doctors', 'request_approves.doctor_id', '=', 'doctors.id')
->select('doctors.*','city_masters.*','request_approves.*');
if($user_id !== "") {
$query = $query->where('request_approves.user_id', 2);
}
if($doctor_id !== "") {
$query = $query->where('request_approves.doctor_id',3);
}
if($start_date !== "" & $end_date !==""){
$query = $query->whereBetween('request_approves.approve_time', array($start_date,$end_date));
}
$query = $query->get();

Answer 2

PHP uses memory to perform queries as well. So performing queries from a PHP application will indeed use more memory than performing them straight from MySQL.
I did a simple calculation and 503316480 bytes comes out to 503MB. So I would suggest modifying your php.ini settings. This should let you output data, and from there you can tune your SQL.
In your php.ini
memory_limit=503M