Python sqlite3占位符

Question

is there a way to set the placeholder for queries in sqlite3 ? I have some functions that work with a database and it would be more satisfying if they could work both with mysql and sqlite. Mysql and Postgres python apis use the %s as a placeholder, but sqlite3 use a question mark instead.

I'm looking for a way to use the same placeholder whatever the database engine.

Thanks for your help.

Answer 1

Updated to fix my earlier error about how to use the paramstyle global

If the DB modules you use follow the Python Database API Specification v2.0 , you can get the module global paramstyle which should be any of these:

1. 'qmark' Question mark style, eg '...WHERE name=?'
2. 'numeric' Numeric, positional style, eg '...WHERE name=:1'
3. 'named' Named style, eg '...WHERE name=:name'
4. 'format' ANSI C printf format codes, eg '...WHERE name=%s'
5. 'pyformat' Python extended format codes, eg '...WHERE name=%(name)s'

You can then compose your SQL statements with the placeholder used by the module. You can do something like this:

import sqlite3

paramstyle = sqlite3.paramstyle

if paramstyle == 'qmark':
    ph = "?"
elif paramstyle == 'format':
    ph = "%s"
else:
    raise Exception("Unexpected paramstyle: %s" % paramstyle)

sql = "INSERT INTO foo VALUES (%(ph)s, %(ph)s, %(ph)s)" % { "ph" : ph }

Answer 2

The underlying library doesn't support %s , so it would need to be replaced manually. It might be easier to check the paramstyle attribute and replace all instances of a different placeholder in the query with an appropriate value instead.