How to join two tables of mysql and concatenate multiple rows into single cell?

Question

How to join two tables of sql and concatenate multiple rows into single cell?

The Query which i am using::

SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
LEFT JOIN Orders
ON Customers.CustomerID=Orders.CustomerID;

Output which i got::

CustomerName          OrderId

John Doe                                     101

John Doe                                     102

John Doe                                     103

John Doe                                     104

Expected Output::

CustomerName          OrderId

John Doe                            101,102,103,104

Answer 1

Group concat is the easiest way to achieve the output you require.

Answer 2

Use GROUP_CONCAT and aggregate by customer to generate a CSV list of orders:

SELECT
    c.CustomerName,
    GROUP_CONCAT(o.OrderID) AS OrderIDs
FROM Customers c
LEFT JOIN Orders o
    ON c.CustomerID = o.CustomerID
GROUP BY
    c.CustomerId;

Note that it would be preferable to aggregate by customer ID, if possible, because perhaps two or more customers have the same name.

Demo