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SQL join table JOIN operator.

We have several options for joining tables in SQL.

The most popular kind of join is through the INNER JOIN operator.

SELECT column_names (1..N) 
      FROM table_name_1 JOIN table_name_2 
	     ON join_condition

Sample code.

Connect the users and comments tables through the id and id_user fields

SELECT * FROM users JOIN comments ON users.id=comments.id_user

Select only the columns: comment date, username and message text.

SELECT comments.date, users.name, comments.text
      FROM users JOIN comments 
           ON users.id=comments.id_user

Let’s put a condition on the name of the user.

SELECT comments.date, users.name, comments.text
      FROM users JOIN comments 
           ON users.id=comments.id_user
               WHERE users.name='Alex'

Let’s sort the request by the date of the comment in descending order.

SELECT comments.date, users.name, comments.text
      FROM users JOIN comments 
           ON users.id=comments.id_user
               WHERE users.name='Alex'
                   ORDER BY comments.date DESC