def export_remote_database(host, username, password, database, export_folder):完善该方法

可以通过以下步骤完善该方法：

1. 导入必要的库：

import os
import subprocess

2. 构造导出命令：

command = f"mysqldump -h {host} -u {username} -p{password} {database} > {export_folder}/{database}.sql"

3. 执行导出命令：

try:
    subprocess.check_call(command, shell=True)
    print(f"{database} database exported successfully to {export_folder}")
except subprocess.CalledProcessError as e:
    print(f"Failed to export {database} database: {e}")

完整的方法如下：

import os
import subprocess

def export_remote_database(host, username, password, database, export_folder):
    command = f"mysqldump -h {host} -u {username} -p{password} {database} > {export_folder}/{database}.sql"
    try:
        subprocess.check_call(command, shell=True)
        print(f"{database} database exported successfully to {export_folder}")
    except subprocess.CalledProcessError as e:
        print(f"Failed to export {database} database: {e}")

这个方法可以将指定的远程数据库导出为一个 SQL 文件，并保存到本地指定的文件夹中。