Question

I have the following scheme:

CREATE TABLE IF NOT EXISTS `connections` (
`username1` varchar(15) NOT NULL,
`username2` varchar(15) NOT NULL,
PRIMARY KEY (`username1`,`username2`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

INSERT INTO `connections` (`username1`, `username2`) VALUES
('guy', 'maricela'),
('maricela', 'guy'),
('mikha', 'guy');

CREATE TABLE IF NOT EXISTS `users` (
`username` varchar(15) NOT NULL,
`first_name` varchar(50) NOT NULL,
`last_name` varchar(50) NOT NULL,  
PRIMARY KEY (`username`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

INSERT INTO `users` (`username`, `first_name`, `last_name`) VALUES
('maricela', 'Maricela', 'Ros'),
('mikha', 'Michael', 'Samuel'),
('guy', 'Guy', 'Marquez');

The scheme contains 2 tables; one for user info called users with info first name,last name, and username. The 2nd table is connections. The column connections.username1 is the one who follows and connections.username2 is the one who is followed. I want to output a list of the people who follow the user maricela and for each result check if the resulting user is followed by the user mikha or not.

I use the following query but checking if the result is followed by mikha isn’t working:

SELECT followed_by_mikha.username AS followed_by_mikha,
   users.first_name,
   users.last_name,       
   users.username      
   FROM connections
   LEFT JOIN users ON users.username = connections.username1
   LEFT JOIN users followed_by_mikha ON (connections.username1 = 'mikha' AND connections.username2 = users.username AND connections.username2 = followed_by_mikha.username)
   WHERE connections.username2 = 'maricela'
   ORDER BY users.username DESC LIMIT 10

Thanks 🙂

Answer 1

SELECT fbm.username2 AS followed_by_mikha,
   users.first_name,
   users.last_name,       
   users.username      
   FROM connections
   LEFT JOIN users ON users.username = connections.username1

   LEFT JOIN connections fbm ON fbm.username2=connections.username1 and fbm.username1 = 'mikha'

   WHERE connections.username2 = 'maricela'
   ORDER BY users.username DESC LIMIT 10