id   first_name   last_name   email                  phone
------------------------------------------------------------------------
1    Michael      Turley      mturley@whatever.com   555-123-4567
2    John         Dohe        jdoe@whatever.com
3    Jack         Smith       jsmith@whatever.com    555-555-5555
4    Johnathan    Doe                                123-456-7890

id   first_name   last_name   email                  phone
------------------------------------------------------------------------
?    John         Doe         jdoe@whatever.com      123-456-7890

DELETE FROM customers WHERE id = 4;

UPDATE customers
SET first_name = 'John',
    last_name  = 'Doe',
    email      = 'jdoe@whatever.com',
    phone      = '123-456-7890'
WHERE id = 2;

UPDATE orders, rewards, receipts
SET customer_id = 2
WHERE customer_id = 4;

use information_schema;
select table_name from columns where column_name = 'customer_id';

SELECT `TABLE_NAME`
FROM `information_schema`.`KEY_COLUMN_USAGE`
WHERE REFERENCED_TABLE_SCHEMA='DATABASE'
  AND REFERENCED_TABLE_NAME='customers'
  AND REFERENCED_COLUMN_NAME='customer_id'