Python-сообщество

import sqlite3
import os

def create_db(dbname):
    if os.path.exists(dbname):
        print("\nWrong name for DB. Try again.\n")
        return
    else:
        db=sqlite3.connect(dbname)
        cursor=db.cursor()
        cursor.execute("Create table STUFF( "
            "id INTEGER NOT NULL , "
            "firstname TEXT NOT NULL , "
            "lastname TEXT NOT NULL , "
            "position TEXT NOT NULL , "
            "salary FLOAT NOT NULL )"
			)
        db.commit()
        return db
def add_empl(db,fname,lname,pos,sal):
    cursor=db.cursor()
    cursor.execute("INSERT INTO STUFF "
        "(firstname, lastname, position, salary) "
        "VALUES (?, ?, ?, ?)"
        (fname, lname, pos, sal))
    db.commit()

from DB import *
db=create_db('dbname')

add_empl(db,'Ioann','Pupkin','programmist', 1000000)

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "DB.py", line 25, in add_empl
    (fname, lname, pos, sal))
TypeError: 'str' object is not callable

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "DB.py", line 25, in add_empl
    (fname, lname, pos, sal))
sqlite3.IntegrityError: STUFF.id may not be NULL