Woocommerce how to write or increment to existing rows in database

Question

I have the following array

[0] => Array (
        [product_id] => 11
        [product_variation] => 0
        [product_count] => 1
    )

[1] => Array (
        [product_id] => 14
        [product_variation] => 18
        [product_count] => 3
    )

[2] => Array (
        [product_id] => 14
        [product_variation] => 18
        [product_count] => 1
    )

Now I want to write this to my database and create clean rows of data. If the product_variation is '0' that means the product is not a variable product. I want to write that to a database row that matches the product_id and increase the product_count in the database accordingly. If the product_variation is not '0' it increase the count in a row that matches the product_variation.

So the end result would contain two rows in my database:

product_id || product_variation || product_count
11            0                    1
14            18                   4

So far I got:

<?php

global $wpdb;
$database_orders = $wpdb->get_results( "SELECT * FROM wp_custom_orders");
$products = array();

//some code to fill $products

foreach ( $products as $product ){
    if ($product['product_variation'] == '0' ) {
        //write to product row where variation is the same
    } else {
        //write to product row where id is the same
    }
}
?>

Now I know about the simple insert/update functions already available and queries using sql but I am not sure how to verify if something already exists in the database and adjust a number properly. Any help would be greatly appreciated!