Question

OK, I need to get some data from multiple tables, all of which have a key.

Projects (key:id)
Projects_users (key:project_id,user_id)
Users (key:id)

Basically each project can have N users on it. I need to get all the users that are in each project in a formatted response.

For instance:

projects = {[

     1: {
          'title':'Project 1',
          'users': [
                1: { id: 23, name:'john' },
                2: { id: 55, name:'sally' }
          ]
     }

     2: {
          'title':'Project 2',
          'users': [
                1: { id: 41, name:'jeff' },
                2: { id: 55, name:'sally' }
          ]
     }

]}

Also, I understand I can do this in PHP with multiple MYSQL statements. Would that be faster and do the concatenation in PHP, or letting MYSQL do this be more efficient / quick.

Answer 1

You can use following statement to get the desired data:

SELECT `Projects`.*, `Users`.* FROM 
    `Projects` JOIN (
        `Projects_users` JOIN 
            `Users` 
            ON `Projects_users`.`user_id` = `Users`.`id`
        ) 
        ON `Projects`.`id` = `Projects_users`.`project_id` 
    ORDER BY `Projects`.`id`

After that, you can traverse the resulting table in single pass and build the array you want.