Joins and correlated subquery - php

Question

Cannot figure out query for situation where I want to display only customers with unverified order but do not include customers who already have at least one verified order. One customer can have more records in DB since for every order also new record in customers table is made so the only way how to track specific user is by customer_number.
My DB structure (simplified):
customers:
id | customer_number
orders:
id | customer_id | isVerified
I would probably need to combine join and correlated queries (to search records in customers table for every customer_number and check isVerified column for false) which in the end could be really slow especially for thousands of records.
I use Laravel so Eloquent ORM is available if this can make things easier.
(Second thought: Or maybe it would be faster and more efficient to rewrite that part to create only one user record for orders of specific user.)
Any ideas? Thank you

Answer 1

There are probably a few ways to do this, but you can achieve this result with a join, aggregation and conditional sum:
select a.customer_id,
sum( case when isVerified = 1 then 1 else 0 end ) as Num_Verified,
sum( case when isVerified = 0 then 1 else 0 end ) as Num_unVerified
from customers as a
left join
orders as b
on a.customer_id = b.customer_id
group by a.customer_id
having Num_Verified = 0
and Num_unVerified > 0
SQLfiddle here

Answer 2

You can achieve like this:
$customer_id = Customer::join('orders','customers.id','orders.cutomer_id')
->where('isVerified',true)
->select('orders.*')
->groupBy('customer_id')
->pluck('customer_id');
This will give customers with at least one verified order.
Now get customers with unverified orders as:
$customers = Customer::join('orders','customers.id','orders.customer_id')
->where('isVerified',false)
->whereNotIn('customer_id',$customer_id)
->select('customers.customer_number','orders.*')
->groupBy('customer_id')
->pluck('customer_id');

Answer 3

How about this one?
$customer_list = customers::where('customer_number',$customer_number)->with('orders',function($query){
$query->where('isVerified',0);
})->get();

Answer 4

One method is an aggregation query:
select c.customer_number
from customers c join
orders o
on c.customer_id = o.customer_id
group by c.customer_number
having sum(isVerified = 1) = 0 and
sum(isVerified = 0) > 0;
This structure assumes that isVerified is a number that takes on the values of 0 for false and 1 for true.