MySQL selecting from multiple tables

Question

im trying to select data from multiple tables, now i am fine with doing it with two tables as i do a query like so:

$myquery = sql_query(
    "SELECT a.object_title, a.published_by, b.userid
     FROM table1 AS a 
     JOIN table2 AS b ON (a.published_by = b.userid)"
);

But see now, i want to select data from a third table, however this third table does not have relationship such as primary key between the first two tables, so i simply want to just pull data from it and form any sort of link with a "JOIN".

How would simply add the third to this query?

Thanks

Write a seperate query? Since it's not related, you don't need to write it in the above query. — davey, Apr 07 '14 at 08:32
I cant do this, as it will overwrite my first query as i need them both in the same section. — user3332590, Apr 07 '14 at 08:34
You could simply do this: `SELECT a.object_title, a.published_by, b.userid, c.id, c.field FROM table1 AS a, table3 as c` Just keep in mind that this will preform a Cartesian product with this table. — Fadey, Apr 07 '14 at 08:37
You should also have a look at this [Q&A](http://stackoverflow.com/questions/12475850/how-can-an-sql-query-return-data-from-multiple-tables) that I wrote which covers a lot of this sort of thing in detail. — Fluffeh, Apr 23 '14 at 11:46

score 2 · Accepted Answer · edited May 23 '17 at 12:23

2

You could use CROSS JOIN :

$myquery = sql_query(
    "SELECT a.object_title, a.published_by, b.userid, c.whatever
     FROM table1 AS a 
     JOIN table2 AS b ON (a.published_by = b.userid)
     CROSS JOIN table3 AS c"
);

I used this other post to find the idea.

More infos here.

edited May 23 '17 at 12:23

Community

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answered Apr 07 '14 at 08:35

Theox

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score 0 · Answer 2 · answered Apr 07 '14 at 08:36

0

Add within you query a Left Join.

answered Apr 07 '14 at 08:36

Matthew Thomas

36
2

score 0 · Answer 3 · edited Apr 23 '14 at 11:31

0

$myquery = sql_query(
            "SELECT a.object_title, a.published_by, b.userid, c.column_name
             FROM Table1 AS a 
             JOIN Table2 AS b ON (a.published_by = b.userid)
             CROSS JOIN Table3 AS c"
);

edited Apr 23 '14 at 11:31

halfer

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answered Apr 07 '14 at 10:27

Mayuri

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MySQL selecting from multiple tables

3 Answers3