import pymysql.cursors

# Connect to the database
connection = pymysql.connect(host='localhost',
                             user='user',
                             password='passwd',
                             db='db',
                             charset='utf8mb4',
                             cursorclass=pymysql.cursors.DictCursor)

with connection.cursor() as cursor:
    sql = "SELECT id, clock from history_log"
    cursor.execute(sql)
    all_history = cursor.fetchall()
    unix_times = []
    for r in all_history:
        unix_times.append(r['clock'])
    unix_times = set(unix_times)

with connection.cursor() as cursor2:
    sql = "SELECT count('*') as c, clock from history_log GROUP BY clock HAVING c>1"
    cursor2.execute(sql)
    dublicates = cursor.fetchall()
    for d in dublicates:
        dublicate_count = d['c']
        while dublicate_count>1:
            dublicate_count-=1
            new_num = free_num(unix_times, d['clock'])
            if new_num != d['clock']
            unix_times.append(new_num)
            update_db(d['clock'], new_num)



def free_num(unix_times, num):
    if num in unix_times:
        return free_num(unix_times, num+1)
    else:
        return num

def update_db(old_num, new_num)     :
    with connection.cursor:
        sql = "UPDATE history_log SET clock="+new_num+" WHERE clock="+old_num+" LIMIT 1"