Python MySQL performs database table changes and queries

#!/usr/bin/python 
 
import MySQLdb 
def doInsert(cursor,db): 
  #insert 
  # Prepare SQL query to INSERT a record into the database. 
  sql = "UPDATE EMPLOYEE SET AGE = AGE+1 WHERE SEX = '%c'" %('M') 
  try: 
    cursor.execute(sql) 
    db.commit() 
  except: 
    db.rollback() 
 
def do_query(cursor,db): 
  sql = "SELECT * FROM EMPLOYEE \ 
     WHERE INCOME > '%d'" % (1000) 
  try: 
    # Execute the SQL command 
    cursor.execute(sql) 
    # Fetch all the rows in a list of lists. 
    results = cursor.fetchall() 
    print 'resuts',cursor.rowcount 
    for row in results: 
      fname = row[0] 
      lname = row[1] 
      age = row[2] 
      sex = row[3] 
      income = row[4] 
      # Now print fetched result 
      print "fname=%s,lname=%s,age=%d,sex=%s,income=%d" % \ 
          (fname, lname, age, sex, income ) 
  except: 
    print "Error: unable to fecth data" 
 
def do_delete(cursor,db): 
  sql = 'DELETE FROM EMPLOYEE WHERE AGE > {}'.format(20) 
  try: 
    cursor.execute(sql) 
    db.commit() 
  except: 
    db.rollback() 
 
def do_insert(cursor,db,firstname,lastname,age,sex,income): 
  sql = "INSERT INTO EMPLOYEE(FIRST_NAME, \ 
    LAST_NAME, AGE, SEX, INCOME) \ 
    VALUES ('%s', '%s', '%d', '%c', '%d' )" % \ 
    (firstname,lastname,age,sex,income) 
  try: 
    cursor.execute(sql) 
    db.commit() 
  except: 
    db.rollback() 
  
# Open database connection 
# change this to your mysql account 
#connect(server,username,password,db_name) 
db = MySQLdb.connect("localhost","root","root","pydb" ) 
# prepare a cursor object using cursor() method 
cursor = db.cursor() 
do_query(cursor,db) 
doInsert(cursor,db) 
do_query(cursor,db) 
do_delete(cursor,db) 
do_query(cursor,db) 
do_insert(cursor,db,'hunter','xue',22,'M',2000) 
do_insert(cursor,db,'mary','yang',22,'f',5555) 
do_insert(cursor,db,'zhang','xue',32,'M',5000) 
do_insert(cursor,db,'hunter','xue',22,'M',333) 
do_query(cursor,db) 
# disconnect from server 
db.close()