Does Python support MySQL prepared statements?
I worked on a PHP project earlier where prepared statements made the SELECT queries 20% faster.
I'm wondering if it works on Python? I can't seem to find anything that specifically says it does or does NOT.
Most languages provide a way to do generic parameterized statements, Python is no different. When a parameterized query is used databases that support preparing statements will automatically do so.
In python a parameterized query looks like this:
cursor.execute("SELECT FROM tablename WHERE fieldname = %s", [value])
The specific style of parameterization may be different depending on your driver, you can import your db module and then do a print yourmodule.paramstyle
.
From PEP-249:
paramstyle
String constant stating the type of parameter marker formatting expected by the interface. Possible values are [2]: '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'
Direct answer, no it doesn't.
joshperry's answer is a good explanation of what it does instead.
From eugene y answer to a similar question,
Check the MySQLdb Package Comments:
"Parameterization" is done in MySQLdb by escaping strings and then blindly interpolating them into the query, instead of using the MYSQL_STMT API. As a result unicode strings have to go through two intermediate representations (encoded string, escaped encoded string) before they're received by the database.
So the answer is: No, it doesn't.
After a quick look through an execute() method of a Cursor object of a MySQLdb package (a kind of de-facto package for integrating with mysql, I guess), it seems, that (at least by default) it only does string interpolation and quoting and not the actual parametrized query:
if args is not None:
query = query % db.literal(args)
If this isn't string interpolation, then what is?
In case of executemany it actually tries to execute the insert/replace as a single statement, as opposed to executing it in a loop. That's about it, no magic there, it seems. At least not in its default behaviour.
EDIT: Oh, I've just realized, that the modulo operator could be overriden, but I've felt like cheating and grepped the source. Didn't find an overriden mod
anywhere, though.