Join table twice - on two different columns of the same table

Question

I have a very confusing database with a table that holds two values I need in a separate table. Here is my issue:

Table1
- id

Table2
- id
- table1_id
- tabl         


        

Answer 1

If you join a table several times, use aliases to distinguish them:

SELECT table1.id,table2.id,table2.table3_id_1,table2.table3_id_2,t3_1.id,t3_2.id
FROM table1
JOIN table2 ON table1.id=table2.table1_id
JOIN table3 t3_1 ON table2.table3_id_1=t3_1.id
JOIN table3 t3_2 ON table2.table3_id_2=t3_2.id
WHERE ... t3_1.id=... AND ... t3_2.id=...