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  • python mysqldb anti sql injection

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)

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
>>> import psycopg2; print psycopg2.paramstyle
>>> import sqlite3; print sqlite3.paramstyle

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 ?


How do I pass parameters to the cursor.execute method?

Don’t use the ‘%’ concatenation operator, pass them as a series of extra parameters. For instance

>>> cursor.execute("SELECT * FROM my_table WHERE my_column = '%s'" % "column_value") 

May do what you want, but more by accident than design. If you change it to;

>>> cursor.execute("SELECT * FROM my_table WHERE my_column = %s", "column_value") 

Then the DB-API module will make sure your value is correctly escaped and turned into an object appropriate for the database.




execute(sql[, parameters])

Executes an SQL statement. The SQL statement may be parameterized (i. e. placeholders instead of SQL literals). The sqlite3module supports two kinds of placeholders: question marks (qmark style) and named placeholders (named style).

Here’s an example of both styles:

import sqlite3

con = sqlite3.connect(":memory:")
cur = con.cursor()
cur.execute("create table people (name_last, age)")

who = "Yeltsin"
age = 72

# This is the qmark style:
cur.execute("insert into people values (?, ?)", (who, age))

# And this is the named style:
cur.execute("select * from people where name_last=:who and age=:age", {"who": who, "age": age})

print cur.fetchone()

execute() will only execute a single SQL statement. If you try to execute more than one statement with it, it will raise a Warning. Use executescript() if you want to execute multiple SQL statements with one call.


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

    # 如果你使用的是 MySQL/PostgreSQL 请一直使用 %s 作为占位符,即便对应的字段是 整型或是其它非字符 类型的值。

    # 不要在占位符那里用 % 拼接,而是在传入的参数那里提前拼接,然后用防注入的方式传入
    c.execute(“SELECT * FROM data WHERE params LIKE %s LIMIT 1”, (“%” + param + “%”,))


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