MySQL double LEFT OUTER JOIN

Question

Into

I have two tables profile and name, the profile table contains some metadata relating to a user. The name table contains all the possible names the profile could have.

I am trying to create a MYSQL query that will give me the profile.age, the given name and family name for all profiles even if that dont have a given name or family name

Tables

Profile

    +-------+---------+
    | ID    | AGE     | 
    +-------+---------+
    | 0     |  10     |
    | 1     |  20     |
    | 2     |  30     |
    | 3     |  40     |
    +-------+---------+  

Name

    +------------+--------+--------+
    | PROFILE_ID |  TYPE  |  NAME  | 
    +------------+--------+--------+
    |      0     |   0    | Jo     |
    |      0     |   1    | Blog   |
    |      1     |   0    | Jim    |
    |      2     |   1    | Smith  |
    +------------+--------+--------+

    Type 0 = Given Name
    Type 1 = Family Name

Quert

This is the Query I am currently using.

SELECT given.name AS 'given_name', family.name AS 'family_name', profile.age
FROM profile
LEFT OUTER JOIN name given ON profile.id = given.profile_id
LEFT OUTER JOIN name family ON profile.id = family.profile_id
WHERE given.type = 0 
AND profile_id.type = 1 
LIMIT 0 , 30

Problem

This is the result I want and expect to get

    +------------+-------------+--------+
    | GIVEN_NAME | FAMILY_NAME | ADE    |
    +------------+-------------+--------+
    | Jo         | Blog        | 10     |
    | Jim        | NULL        | 20     |
    | NULL       | Smith       | 30     |
    | NULL       | NULL        | 40     |
    +------------+-------------+--------+

However this is what I actually get

    +------------+-------------+--------+
    | GIVEN_NAME | FAMILY_NAME | AGE    |
    +------------+-------------+--------+
    | Jo         | Blog        | 10     |
    +------------+-------------+--------+

From what I understand LEFT OUTER JOIN should return on the NULL value joins. What am I doing wrong? How do I change my Query to return the NULL value joun?

Answer 1

As soon as you have a WHERE clause on a table that is being LEFT JOINed on then you will immediately eliminate the NULL rows (i.e. where there is no match). So for starters, you should move the condition of given.type = 0 to the ON clause instead of in the WHERE clause. And I'm going to assume there is an issue with your other condition on the WHERE clause.

SELECT given.name AS 'given_name', family.name AS 'family_name', profile.age
FROM profile
LEFT OUTER JOIN name given ON profile.id = given.profile_id AND given.type = 0 
LEFT OUTER JOIN name family ON profile.id = family.profile_id AND family.type = 1
LIMIT 0 , 30

Answer 2

You are filtering type to be 0 or 1(in where clause), this will ommit nulls.

SELECT given.name AS 'given_name', family.name AS 'family_name', profile.age
    FROM profile
    LEFT OUTER JOIN name given 
       ON profile.id = given.profile_id and given.type = 0 
    LEFT OUTER JOIN name family 
       ON profile.id = family.profile_id and profile.type = 1 
    LIMIT 0 , 30