Question

I’m running MySQL 5.0.88 and need to select data from two tables, called articles and media.

When uploading images to my server I need to query all articles of a user and see whether there is already a path specified in the media table (field type="img") to avoid running unnecessary overwrites.

I had hoped to just include the m.type in my query, but I can’t get it to work.

My query looks like this:

SELECT DISTINCT a.style, a.filename, a.path, m.type
    FROM articles AS a
    LEFT JOIN mnedia AS m
       ON a.iln = m.iln
    WHERE
       a.iln = id_12345
       AND m.type = "img"
       AND m.type IS NOT NULL

This gives me ALL articles (correct) of user id_12345, but the type field is alway img although the media table only has one record for article abc.

Question:
How do I need to query, so it returns all articles of a user (working) displaying type=NULL for articles, which are NOT listed in table media and type="img" for articles, which are listed in the table media(such as abc)?

Thanks for help!

EDIT:
table articles may include records:

abc 
d
e
f
g

table media may include

abc type=img

the query should return:

abc type=img
d type=NULL
e type=NULL
f type=NULL
g type=NULL

EDIT:
I also woudn’t mind getting all records in articles that are not in media, such as on this image, 2nd join left hand side (“b.Key IS NULL)

SOLUTION:
Ok. I needed to check for another field besiders user_id when joining both tables. This is how it works:

SELECT DISTINCT a.style, a.filename, a.path, m.type
    FROM articles AS a
    LEFT JOIN mnedia AS m
       ON a.iln = m.iln
       AND a.style= m.style
    WHERE
       a.iln = id_12345
       AND ( m.type = "img" OR m.type IS NULL )

THANKS ALL for your suggestions!

Answer 1

you should put m.type = "img" condition on LEFT JOIN instead of putting it in WHERE clause:

SELECT DISTINCT a.style, a.filename, a.path, m.type
FROM articles AS a
     LEFT JOIN mnedia AS m
         ON a.iln = m.iln
            AND m.type = "img"
WHERE a.iln = id_12345;