Contents
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
Example
SELECT column_name(s)
FROM mytable1
LEFT JOIN mytable2 ON mytable1.column_name = mytable2.column_name;Demo Database
This is demo example from the "Developers" table in the database:
| ID | Name | City | Country |
|---|---|---|---|
| 1 | Tom Kurkutis | New York | USA |
| 2 | Ana Fernandez | London | UK |
| 3 | Antonio Indigo | Paris | France |
| 4 | Aarav Kaelin | Delhi | India |
| 5 | Andrew Tumota | Miami | USA |
This is demo example from the "Orders" table in the database:
| ID | Customer_ID | Employee_ID |
|---|---|---|
| 20408 | 2 | 7 |
| 20409 | 2 | 5 |
| 85471 | 1 | 3 |
| 75864 | 5 | 8 |
SQL LEFT JOIN: Example
In this example, we'll return all developers, and their orders:
Example
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).