SQL JOIN

A JOIN clause is used to combine rows from two or more tables, based on a related column between them.

 

Customers table:

customer_id fullname
1 Kailash
2 Amit
3 Siddarth
4 Vikas

Orders table:

order_id amount customer
1 2000 2
2 3000 4
3 3500 5
4 2500 7

 

Here, the SQL command selects customer_id and fullname columns (from the Customers table) and the amount column (from the Orders table).

Query:

SELECT Customers.customer_id, Customers.fullname, Orders.amount
FROM Customers
JOIN Orders
ON Customers.customer_id = Orders.customer;

 

And, the result set will contain those rows where there is a match between customer_id (of the Customers table) and customer (of the Orders table).

Result:

customer_id fullname amount
2 Amit 2000
4 Vikas 3000