Matching Data From Multiple Tables with SQL LEFT JOIN

SQL LEFT JOIN: Main Tips

• LEFT JOIN can be called LEFT OUTER JOIN.
• If there is no match, the result is NULL.

SQL LEFT JOIN Keyword

Returns all information from the left table (mytable1), and the matched information from the right table (mytable2).

Syntax of SQL LEFT JOIN

SELECT column_name(s)
FROM mytable1
LEFT JOIN mytable2 ON mytable1.column_name = mytable2.column_name;

Theory is great, but we recommend digging deeper!

Course on How to Use SQLite: Creation and Management of SQLite Databases

Frank Anemaet

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Demo Database

This is demo example from the "Developers" table in the database:

This is demo example from the "Orders" table in the database:

SQL LEFT JOIN: Example

In this example, we'll return all developers, and their orders:

SELECT Developers.Name, Customer_orders.ID
FROM Developers
LEFT JOIN Customer_orders ON Developers.ID = Customer_orders.customer_id
ORDER BY Developers.Name;

Note: LEFT JOIN returns all the left table rows from (Developers), even if finding matches in the right table (Orders).