Inner joins

Understanding join queries

Join queries allow us to combine data from two or more tables and return them as a single response.

username	content	createdAt
EluskM	Just bought Mars. Renaming it to Elusk Planet. #SpaceX	2023-08-15 14:30:00
OprahWindey	You get a car! You get a car! Everybody gets a car! #Giveaway	2023-07-22 13:00:00
OprahWindey	My next book club pick is the dictionary. I hear it's a page-turner. #ReadMore	2023-07-25 17:30:00
MeghanTrainer	All about that bass? More like all about that space. @EluskM, need a backup singer on Mars?	2023-05-20 15:00:00

The username value comes from the users table, but the content and created at values come from the bleets table.

Writing an inner join query

We write an inner join query using table.column to select the columns, and then specifying the condition on which two rows should be joined together.

SELECT users.username, bleets.content, bleets.createdAt
FROM users
INNER JOIN bleets ON users.id = bleets.userId;

It is good to know that join queries can be combined with other SQL commands, such as WHERE, ORDER BY and LIMIT.

SELECT users.username, bleets.content, bleets.createdAt
FROM users
INNER JOIN bleets ON users.id = bleets.userId
ORDER BY bleets.impressions DESC
LIMIT 5;