Python: IF在SQLITE3中不起作用

import sqlite3

# 连接到SQLite数据库
conn = sqlite3.connect('example.db')
cursor = conn.cursor()

# 创建一个示例表
cursor.execute('''CREATE TABLE IF NOT EXISTS example_table
                  (id INT PRIMARY KEY NOT NULL,
                   name TEXT NOT NULL,
                   age INT NOT NULL)''')

# 插入示例数据
cursor.execute("INSERT INTO example_table (id, name, age) VALUES (1, 'Alice', 25)")
cursor.execute("INSERT INTO example_table (id, name, age) VALUES (2, 'Bob', 30)")

# 使用CASE语句进行条件判断和分支处理
cursor.execute("SELECT id, name, CASE WHEN age < 30 THEN 'Young' ELSE 'Old' END FROM example_table")

# 获取查询结果
result = cursor.fetchall()
for row in result:
    print(row)

# 关闭数据库连接
conn.close()