当有效变量的数量最初未知时，如何添加到Postgresql where子句？

import psycopg2

def build_dynamic_query():
    # 假设有一组变量用于构建WHERE子句
    variables = ["var1", "var2", "var3"]

    # 初始化动态SQL字符串
    dynamic_sql = "SELECT * FROM table_name WHERE "

    # 构建WHERE子句
    for index, var in enumerate(variables):
        # 添加变量到WHERE子句
        dynamic_sql += f"{var} = %s"

        # 添加AND运算符（除非是最后一个变量）
        if index < len(variables) - 1:
            dynamic_sql += " AND "

    # 返回构建好的动态SQL语句
    return dynamic_sql

# 连接到PostgreSQL数据库
conn = psycopg2.connect(database="your_database", user="your_username", password="your_password", host="your_host", port="your_port")

# 创建游标
cur = conn.cursor()

# 构建动态SQL语句
dynamic_query = build_dynamic_query()

# 假设有一组变量的值
variable_values = ["value1", "value2", "value3"]

# 执行动态SQL语句
cur.execute(dynamic_query, variable_values)

# 获取查询结果
results = cur.fetchall()

# 关闭游标和数据库连接
cur.close()
conn.close()