How to use variables in SQL statement in Python?

Question

Ok so I'm not that experienced in Python.

I have the following Python code:

cursor.execute("INSERT INTO table VALUES var1, var2, var3,")

where var1 is an integer, var2 & var3 are strings.

How can I write the variable names without python including them as part of the query text?

Answer 1

cursor.execute("INSERT INTO table VALUES (%s, %s, %s)", var1, var2, var3)

The database API does proper escaping and quoting of variables. Be careful not to use the string formatting operator (%), because it does not do any escaping or quoting.

Answer 2

http://www.amk.ca/python/writing/DB-API.html

Be careful when you simply append values of variables to your statements: Imagine a user naming himself ';DROP TABLE Users;' -- That's why you need to use sql escaping, which Python provides for you when you use the cursor.execute in a decent manner. Example in the url is:

cursor.execute("insert into Attendees values (?, ?, ?)", (name,
seminar, paid) )

Answer 3

Different implementations of the Python DB-API are allowed to use different placeholders, so you'll need to find out which one you're using -- it could be (e.g. with MySQLdb):

cursor.execute("INSERT INTO table VALUES (%s, %s, %s)", (var1, var2, var3))

or (e.g. with sqlite3 from the Python standard library):

cursor.execute("INSERT INTO table VALUES (?, ?, ?)", (var1, var2, var3))

or others yet (after VALUES you could have (:1, :2, :3) , or "named styles" (:fee, :fie, :fo) or (%(fee)s, %(fie)s, %(fo)s) where you pass a dict instead of a map as the second argument to execute). Check the paramstyle string constant in the DB API module you're using, and look for paramstyle at http://www.python.org/dev/peps/pep-0249/ to see what all the parameter-passing styles are!