Python Sqlite3 - Data get overwritten

When ever i try to insert data to my database, it's like it simply just overwrite whole file or not saving it correctly. My thoughts about this script was that if i ran it multiple times it would output this:

(1, 126)
(2, 127)
(3, 126)
(4, 127)

I also now that if i doesn't create table within the script, it gives me an error that the table doesn't exist, even though the table was created, last time i ran the script.

import sqlite3

# Connecting to the database file
conn = sqlite3.connect("MyDB.db")
c = conn.cursor()

# Check if table exists
c.execute("DROP TABLE IF EXISTS t1")


# Create table
c.execute('''CREATE TABLE t1(
             a INTEGER PRIMARY KEY,
             b INTEGER);''')

# Insert value
c.execute('''INSERT INTO t1 VALUES(NULL,126);''')
c.execute('''INSERT INTO t1 VALUES(NULL,127);''')

# Save changes
conn.commit()

for row in c.execute('SELECT * FROM t1'):
        print(row)

# Output:
# (1, 126)
# (2, 127)
conn.close()

I really want this to work, since i'm working on a school project where my product is to make a functional store where you can add, remove products and sort them by date they were added.