Question

I have three different tables in MySQL:

given an user id, how can i get a list of role’s name of this user?
For example, user_id = 1
I need a list like this (1, deleteuser, modifyuser, viewuser)

How can I construct my SQL command to get such a list?

Answer 1

JOIN the three tables like so:

SELECT 
  u.id,
  r.Name
FROM user u
INNER JOIN user_role ur ON u.id = ur.user_id
INNER JOIN roles r ON ur.Role_id = r.id
WHERE u.id = Someid

However, if you want the list of roles for each user to be concatenated into one string. Use GROUP_CONCAT like so:

SELECT 
  u.id,
  GROUP_CONCAT(r.Name) roles
FROM user u
INNER JOIN user_role ur ON u.id = ur.user_id
INNER JOIN role r ON ur.Role_id = r.id
WHERE u.id = 1
GROUP BY u.id

SQL Fiddle Demo