Generate SQL statements with python [duplicate]

Question

I need to generate a list of insert statements (for postgresql) from html files, is there a library available for python to help me properly escape and quote the names/values? in PHP i use PDO to do the escaping and quoting, is there any equivalent library for python?

Edit: I need to generate a file with sql statements for execution later

Answer 1

I know this is an old question, but I've often wanted what it seems the OP wants: A VERY simple library for generating basic SQL.

The below functions do just that. You give them a table name and a dictionary containing the data you want to use and they return the SQL query for the operation you need.

The key/value pairs represent field names and values in the database rows.

def read(table, **kwargs):
    """ Generates SQL for a SELECT statement matching the kwargs passed. """
    sql = list()
    sql.append("SELECT * FROM %s " % table)
    if kwargs:
        sql.append("WHERE " + " AND ".join("%s = '%s'" % (k, v) for k, v in kwargs.iteritems()))
    sql.append(";")
    return "".join(sql)


def upsert(table, **kwargs):
    """ update/insert rows into objects table (update if the row already exists)
        given the key-value pairs in kwargs """
    keys = ["%s" % k for k in kwargs]
    values = ["'%s'" % v for v in kwargs.values()]
    sql = list()
    sql.append("INSERT INTO %s (" % table)
    sql.append(", ".join(keys))
    sql.append(") VALUES (")
    sql.append(", ".join(values))
    sql.append(") ON DUPLICATE KEY UPDATE ")
    sql.append(", ".join("%s = '%s'" % (k, v) for k, v in kwargs.iteritems()))
    sql.append(";")
    return "".join(sql)


def delete(table, **kwargs):
    """ deletes rows from table where **kwargs match """
    sql = list()
    sql.append("DELETE FROM %s " % table)
    sql.append("WHERE " + " AND ".join("%s = '%s'" % (k, v) for k, v in kwargs.iteritems()))
    sql.append(";")
    return "".join(sql)

You use it like so. Just give it a table name and a dictionary (or use the **kwargs feature of python):

>>> upsert("tbl", LogID=500, LoggedValue=5)
"INSERT INTO tbl (LogID, LoggedValue) VALUES ('500', '5') ON DUPLICATE KEY UPDATE LogID = '500', LoggedValue = '5';"

>>> read("tbl", **{"username": "morten"})
"SELECT * FROM tbl WHERE username = 'morten';"

>>> read("tbl", **{"user_type": 1, "user_group": "admin"})
"SELECT * FROM tbl WHERE user_type = '1' AND user_group = 'admin';"

But BEWARE OF SQL INJECTION ATTACKS

Look what happens when a malicious user of your code does this:

>>> read("tbl", **{"user_group": "admin'; DROP TABLE tbl; --"})
"SELECT * FROM tbl WHERE user_group = 'admin'; DROP TABLE tbl; --';"

It's easy to make your own makeshift ORM but you only get what you see -- you have to escape the input yourself :)

Answer 2

SQLAlchemy provides a robust expression language for generating SQL from Python.

Like every other well-designed abstraction layer, however, the queries it generates insert data through bind variables rather than through attempting to mix the query language and the data being inserted into a single string. This approach avoids massive security vulnerabilities and is otherwise The Right Thing.