MySQLdb : double quotes passed to the query

Question

I'm getting mad with MySQLdb ! I'm following exactly the official doc but I have an error with the code :

DB_TABLE = "test"
cursor.execute("SELECT MAX(id) AS maxid FROM " + DB_TABLE)
print "***"
cursor.execute("SELECT MAX(id) AS maxid FROM %s" , (DB_TABLE,))

I get the error :

Traceback (most recent call last):
  File "dbscript.py", line 49, in <module>
    cursor.execute("SELECT MAX(id) AS maxid FROM %s" , (DB_TABLE,))
  File "build/bdist.macosx-10.7-intel/egg/MySQLdb/cursors.py", line 174, in execute
  File "build/bdist.macosx-10.7-intel/egg/MySQLdb/connections.py", line 36, in defaulterrorhandler
_mysql_exceptions.ProgrammingError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''test'' at line 1")

Obviously there is a problem with some quotes. My command seems to send a line like this to MySQL :

SELECT MAX(id) AS maxid FROM ''test''

How can I change the double quote by a single one ?

I'v tried the followings :

DB_TABLE = 'test'
cursor.execute("SELECT MAX(id) AS maxid FROM %s" , [DB_TABLE])
cursor.execute("SELECT MAX(id) AS maxid FROM %s" , ("test",))

But nothing works :(

Answer 1

cursor.execute("SELECT MAX(id) AS maxid FROM %s" , ("test",)) 

and in similar statements, the cursor.execute will substitute SQL parameters into %s.

What you need is something like this

sql = "SELECT MAX(id) AS maxid FROM %s" % ("test", )
cursor.execute(sql)

Answer 2

You cannot parameterized table name, so you have to sanitize it yourself and use string substitution in the query instead.

To sanitize a table name in a query with multiple parameters:

query = "SELECT * FROM %s WHERE columnName = %s" % (tableName,'%s')
print(query)

At this point, query will display as:

SELECT * FROM tableName WHERE columName = %s

Once you've constructed your cursor, use the parameterized condition:

cursor.execute(query,(columnValue,))

The actual query that mySQL will read in then is:

SELECT * FROM tableName WHERE columnName = columnValue

If you try to pass in a table name without sanitizing it, you'll get a syntax error.