"OperationalError: no such column: " in python + sqlite3

Phenomenon

When I try to add data to the database using sqlite3 in python, I get "Operational Error: no such column: None".

It reproduce with the following code. Suppose the examples table has a column value of type integer. Store the value of the variable x created inside python as value.

The environment is python 3.7　sqlite 3.30.0

import sqlite3

db_path="test.sqlite3"

con=sqlite3.connect(db_path)
c=con.cursor()
x=1
sql="insert into examples(value) values({0})".format(x)
c.execute(sql)

con.commit()
con.close()

There is no problem with x = 1. However, if x = None,

OperationalError: no such column: None

Cause

Because I used .format (), "None" became a string. To be correct, write as follows. This was also officially recommended.

#~~~omit~~~~
x=None
sql="insert into examples(value) values(?)"
c.execute(sql, [x])
#~~~omit~~~~