format a string with Python from list elements

Question

I have a list that contains two elements like this :

tr = ['table1', 'table2']

I would like to be able to generate a part of a query and get this :

table1 INNER JOIN table2 ON table1.id = table2.id

How can I do this please in Python ?

Any help would be appreciated.

EDIT : Here is what I've tried to produce table1 INNER JOIN table2:

join_tables = ('%s LEFT JOIN %s'.format(' '.join('%s' for _ in range(element -1))) for element in tr)

• Martijn Pieters: It looks like you want us to write some code for you. While many users are willing to produce code for a coder in distress, they usually only help when the poster has already tried to solve the problem on their own. A good way to demonstrate this effort is to include the code you've written so far, example input (if there is any), the expected output, and the output you actually get (console output, stack traces, compiler errors - whatever is applicable). The more detail you provide, the more answers you are likely to receive.

Answer 1

"{0} INNER JOIN {1} ON {0}.id = {1}.id".format("table1", "table2")

Edit

If this was a legitimate example, you need to use cursor.execute("{0} INNER JOIN {1} ON {0}.id = {1}.id", ("table1", "table2")) for MySQL, or cursor.mogrify(...) for Postgres to properly escape the table names and prevent SQL injection.

• Jeremy Roman: With the usual caveat of "if these are coming from the user, be sure you validate them".
• dav: @JeremyRoman he shouldn't even be using string formatting if this is going to be directly used in a database.
• salamey: @dav can you please tell me why i should not be using string formatting for the database? what should I do then ?
• Jeremy Roman: dav: Oh, you'll get no argument from me on the merits of proper escaping or, better yet, prepared statements. Just pointing out that this question looks like it leads down the road to SQL injection. :)