Question

I have this comment table where users can post comment as well as guest, i can fetch users comments like this

SELECT `comments`.`user_id`, `comments`.`pubdate`,    `comments`.`comment`,
`comments`.`guest_name`,
`comments`.`id`, 
`users`.`username`, 

FROM (`comments`) 
JOIN `users` ON `comments`.`user_id` = `users`.`user_id` 
WHERE `item_id` = '64' AND `section` = 'blog'

problem is guest users don’t have user id hence thier id goes to db as 0 so it is not displayed, how can i show comments of both users and guest ?

Answer 1

You should use LEFT JOIN

SELECT `comments`.`user_id`, `comments`.`pubdate`,    `comments`.`comment`,
        `comments`.`guest_name`,
        `comments`.`id`, 
        `users`.`username`, 

FROM `comments`
LEFT JOIN `users` ON `comments`.`user_id` = `users`.`user_id` 
WHERE `item_id` = '64' AND `section` = 'blog'

If there’s no matching user for comments.user_id, then users.username will be NULL.