如何在Python的SQLite3中允许占位符为空？

import sqlite3

conn = sqlite3.connect('database.db')
cursor = conn.cursor()

sql = "INSERT INTO table_name (column1, column2, column3) VALUES (?, ?, ?)"
values = ('value1', None, 'value3')  # 将占位符的值设置为None
cursor.execute(sql, values)

conn.commit()
conn.close()

import sqlite3

conn = sqlite3.connect('database.db')
cursor = conn.cursor()

sql = "SELECT * FROM table_name WHERE column1 = ?"
value = ''  # 将占位符的值设置为空字符串
cursor.execute(sql, (value,))

result = cursor.fetchall()

conn.close()