mysql plusieurs colonnes recherche

Question

essayer de construire une requête de quelques tables ici, et se déconcerté sur le finaliser:

Tableau 1 (circuits)

t1.circuit_id 
t1.circuit_name 

(données-échantillon)

1234, test1 
1235, test2 
1236, test3 

Tableau 2 (comptes)

t2.account_id 
t2.account_username 

(données d'échantillon)

100, user1 
101, user2 
102, user3 

Tableau 3 (missions)

t3.circuit_id 
t3.assignment1 (references table 2 (account_id)) 
t3.assignment2 (references table 2 (account_id)) 
t3.assignment3 (references table 2 (account_id)) 

(données-échantillon)

1234, 100, 101, 102 
1235, 101, 101, 101 
1236, 102, 102, 102 

Ce que je suis après un résultat comme suit:

t1.circuit_id, t3.assignment1, t2.account_username, t3.assignment2, t2.account_username, t3.assignment3, t2.account_username. 

1234, 100, user01, 101, user02, 102, user03 
1235, 101, user02, 101, user02, 101, user02 
1236, 102, user03, 102, user03, 102, user03 

Un grand merci, --a

Answer 1

SELECT t3.circuit_id, t3.assignment1, t21.account_username, t3.assignment2, t22.account_username, t3.assignment3, t23.account_username 
FROM t3 
LEFT JOIN 
     t2 t21 
ON  t21.account_id = t3.assigment1 
LEFT JOIN 
     t2 t22 
ON  t22.account_id = t3.assigment2 
LEFT JOIN 
     t2 t23 
ON  t23.account_id = t3.assigment3