Question

So, I am not sure what the best way to do a join for these tables was. I want to use a JOIN because I believe it is faster than bring all three of the tables in on FROM. So, if i have three tables…

Table1
--id
--data

Table2
--id
--data

Table1_Table2
--table1_id
--table2_id

How can I do a join for this data using the join table?

Answer 1

Mentioning all tables in the FROM clause is also a join, implicit one. It is not recommended to use it as it might lead to a Cartesian product of the tables involved in case you’ll forget to add predicates in the WHERE clause.

Have a look on the Wikipedia JOIN article and also at this very nice blogpost about joins by Jeff Atwood.

I think that you’re interested in the INNER JOIN between the tables, although other variants exists. Try this:

SELECT t1.*, t2.*
  FROM Table1 t1
  INNER JOIN Table1_Table2 tt ON t1.id = tt.table1_id
  INNER JOIN Table2 t2 ON t2.id = tt.table2_id;

I skipped Table1_Table2 columns from the select list, as there’s nothing special there.