Can I automate the “on” statement from MySQL queries?

Question

Background

In the process of QA/QC, I am writing lots of queries with multiple joins. I am using MySQL.

I would like to know how (if) I can simplify join statements, e.g. by setting default fields to join on.

My tables are named with a plural form of the object that they contain:

 names
 types
 actions
 surnames
 names_surnames

where names_surnames is a many-many lookup table

the primary keys are always id and the foreign keys are always, e.g.

 names.type_id
 names.action_id
 names_surnames.name_id
 names_surnames.surname_id

My joins would be something like

select names.col1 
from names join types on names.type_id = type.id
           join actions on names.action_id = actions.id;

Question

Is there a way to get MySQL to always assume that tables will be joined with on thistables.thattable_id = thattable.id?

Answer 1

How about creating views for joins that are used repeatedly ?

For example:

create view my_view as 
select names.id as name_id, names.type_id, names.action_id, ...
from names join types on names.type_id = type.id
           join actions on names.action_id = actions.id;

Answer 2

If the columns were named the same in "both" tables, I think you could use NATURAL JOIN. Although that won't work for you, your consistency in naming should still let you generate queries--or at least the join clauses--with a scripting language.

Answer 3

If the tables involved in the JOIN share identically named fields,
then you can use the USING clause of the JOIN syntax.

For example

IF the actions table had action_id as the primary key instead of id
and the types table had type_id as the primary key instead of id

THEN the query could be rewritten as

select names.col1 
from names join types USING (type_id)
           join actions USING (action_id);

Give it a Try !!!