Question

I am a newbie at MySQL….. I am trying to left join 3 tables one contains some_id,name,count,descr and second one has id,some_id,uni_id and the last one has uni_id,price,added,etc So when i try to join these three tables it says that there’s no such field named descr

What could be the best way to join these tables without modifying structure of them?

Answer 1

Assuming the following schema:

• table1(some_id, name, count, descr), where some_id is the primary key;
• table2(id, some_id, uni_id), where some_id is a foreign key to table1;
• table3(uni_id, price, added), where uni_id is a foreign key to table2.

All you need to do is a LEFT OUTER JOIN between the three tables:

SELECT *
FROM table1 t1 LEFT JOIN table2 t2 ON (t1.some_id = t2.some_id)
  LEFT JOIN table3 ON (t2.uni_id = t3.uni_id)

References:

• Left Outer Join
• Join Syntax