Simple JOINs recap
Various kinds of JOINs
Filtering with LEFT JOIN and RIGHT JOIN
Instruction
Alright! The easiest and most basic way to join two tables is to use the JOIN clause. Take a look:
SELECT full_name, name FROM position JOIN employee ON position.id = employee.position_id
As you can see, we simply list the name of the first table after the FROM clause as usual. Then, we put the keyword JOIN. And after that we specify the name of the second table.
The ON keyword allows us to specify the condition upon which we should join two tables. In our example, the database joins only those rows from both tables for which the value under the ID column of the table position is equal to the value under the position_id column of the employee table.
| employee | position | ||
|---|---|---|---|
| full_name | position_id | id | name |
| Mark Zucchero | 1 | 1 | Java Developer |
| Sara Darling | 2 | 2 | Marketing Specialist |
| Joe Doe | 3 | 3 | Java Developer |
Exercise
Join the author table with the book table.
Select the title of each book and the name of its author.
Stuck? Here's a hint!
Type:
SELECT title, name FROM author JOIN book ON author.id = book.author_id
