Question

I am looking for a nice “pythonic” and “SQL-Injection-free” solution for a problem with reserved words in MySQL.

I have the following code:

alter_sql = 'ALTER TABLE %s ADD COLUMN %s TEXT'      
cursor.execute(alter_sql, sql_params)

The problem occurs when column name is something like ‘index’, ‘int’, ‘limit’ ….

In MySQL shell I can do:

ALTER TABLE test ADD COLUMN test.limit;

or

ALTER TABLE test ADD COLUMN `limit`;

but not

ALTER TABLE test ADD COLUMN 'test.limit';

How can I achieve that with Python and MySQLdb?

Answer 1

Maybe this will work:

alter_sql = 'ALTER TABLE `%s` ADD COLUMN `%s` TEXT'

UPDATE: This seems not to work, because binding parameters this way will add single quotes, as MySQLdb supposes this is a string literal.

Alternatively, you can append the table name before the column name?

table_name = MySQLdb.escape_string(table_name)
escaped_column_name = MySQLdb.escape_string(column_name)
column_name = '`%s`.`%s`' % (table_name, escaped_column_name)

alter_sql = 'ALTER TABLE %s ADD COLUMN %s TEXT' % (table_name, column_name)

This way, you must escape them manually, to avoid binding them and adding single quotes around it.