How to concatenate columns in a Postgres SELECT?

Question

I have two string columns a and b in a table foo.

select a, b from foo returns values a and b<

Answer 1

PHP's Laravel framework, I am using search first_name, last_name Fields consider like Full Name Search

Using || symbol Or concat_ws(), concat() methods

$names = str_replace(" ", "", $searchKey);                               
$customers = Customer::where('organization_id',$this->user->organization_id)
             ->where(function ($q) use ($searchKey, $names) {
                 $q->orWhere('phone_number', 'ilike', "%{$searchKey}%"); 
                 $q->orWhere('email', 'ilike', "%{$searchKey}%");
                 $q->orWhereRaw('(first_name || last_name) LIKE ? ', '%' . $names. '%');
    })->orderBy('created_at','desc')->paginate(20);

This worked charm!!!