仅在非空的情况下才在where子句中使用变量？一种动态where子句？

import pymysql

# 连接数据库
conn = pymysql.connect(host='localhost', user='root', password='password', db='test', charset='utf8mb4')

# 构建动态WHERE子句
where_clause = "age > %s"

# 绑定参数
params = (18,)

# 执行查询
with conn.cursor() as cursor:
    sql = "SELECT * FROM users WHERE " + where_clause
    cursor.execute(sql, params)
    results = cursor.fetchall()

# 输出结果
for row in results:
    print(row)