How to UPDATE rows in one table where there duplictaes in another - php

Question

I would be massively grateful if someone can help me write a query to update our orders system due to a dupe issue.
We have an orders table and a customers table.
I've identified some duplicate rows in our customers table where the email address and password are the same on unique rows - and are associated with unique live orders by CustomerNumber which exists in each table. This is bad as when a customer logs in to their account, they won't see all of their orders, rather they'll only see the orders associated with the highest customer ID (see login SQL below)
Identify duplicate user accounts:
SELECT
emailaddress,
PASSWORD,
count(*)
FROM
scustomers
JOIN orders ON orders.customernumber = customers.CustomerNumber
WHERE Completed = 1
GROUP BY
emailaddress,
PASSWORD
HAVING
count(*) > 1
Login SQL:
SELECT * FROM scustomers WHERE EmailAddress = :EmailAddress AND (Password = :Password) ORDER BY CustomerNumber DESC LIMIT 0,1
I need to write a query that:
Updates the "orders" table
Updates the "CustomerNumber" column
Sets the "CustomerNumber" column to be the highest "CustomerNumber"
WHERE the "customers" table has more than 1 rows with has an
identical "Email" and "Password" column
Where do I start?!
Our system has been fixed so that any customer order a new product by logging in will always use the highest possible associated CustomerNumber so this really is about fixing existing data.
UPDATE:
I've never used SQL Fiddle, but here is some sample data that I hope will help you.. help me!
CUSTOMERS:
customernumber, email, password
3272, jwilson#email.com, 9a098e0bade9b4f2ac4ecdf86111cf7e
10001, jwilson#email.com, 9a098e0bade9b4f2ac4ecdf86111cf7e
ORDERS:
ordernumber,customernumber,status
123457, 3272, 'LIVE'
123456, 10001, 'LIVE'
I need to update OrderNumber: 123457 to have the CustomerNumber of 10001, not 3272.

Answer 1

Step 1 : create a temporary column to store the correct CustomerNumber
ALTER TABLE scustomers
ADD COLUMN id_tmp INT NOT NULL;
Step 2 : retrieve the correct CustomerNumber
UPDATE scustomers
INNER JOIN
(
SELECT
emailaddress,
PASSWORD,
MAX(CustomerNumber) AS id
FROM
scustomers
GROUP BY
emailaddress,
PASSWORD
) AS duplicate ON scustomers.emailaddress = duplicate.emailaddress AND scustomers.PASSWORD = duplicate.PASSWORD
SET id_tmp = id;
Step 3 : update order table with the correct CustomerNumber
UPDATE orders
INNER JOIN scustomers ON orders.customerNumber = customers.CustomerNumber
SET orders.customernumber = id_tmp;
Step 4 : delete duplicate customers
DELETE FROM scustomers
WHERE customernumber <> id_tmp;
Step 5 : remove the temporary column
ALTER TABLE scustomers
DROP COLUMN id_tmp;

Answer 2

I am just giving idea about sql query you need to write for loop
SELECT GROUP_CONCAT( customernumber) , i.email
FROM scustomers i INNER JOIN ( SELECT k.email FROM scustomers k GROUP BY k.email
HAVING COUNT( `customernumber` ) >1 )j ON i.email = j.email GROUP BY i.email
Out put :
----------------------------
customernumber Email
---------------------------
1,2,3 ss#ss.ss
After this all duplicate will come in on field.explode the new customernumber get last value in that array (Ex: 3 is last value)
update `orders` set `customernumber`='last array value(Ex: 3)' WHERE `customernumber` in (customernumber from above query(1,2,3) )
For delete duplicate records
DELETE n1 FROM scustomers n1, scustomers n2 WHERE n1.customernumber< n2.customernumber AND n1.email= n2.email