python.md

Python

Using the Python DB API, don't do this:

# Do NOT do it this way.
cmd = "update people set name='%s' where id='%s'" % (name, id)
curs.execute(cmd)

Instead, do this:

cmd = "update people set name=%s where id=%s"
curs.execute(cmd, (name, id))

Note that the placeholder syntax depends on the database you are using.

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

The values for the most common databases are:

>>> import MySQLdb; print MySQLdb.paramstyle
format
>>> import psycopg2; print psycopg2.paramstyle
pyformat
>>> import sqlite3; print sqlite3.paramstyle
qmark

So if you are using MySQL or PostgreSQL, use %s (even for numbers and other non-string values!) and if you are using SQLite use ?

To do

• Add some narrative.