怎么释放mysql连接

import mysql.connector

# 建立连接
cnx = mysql.connector.connect(user='user', password='password', host='host', database='database')

# 执行操作...

# 关闭连接
cnx.close()

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class MySQLConnectionExample {
    public static void main(String[] args) {
        Connection conn = null;
        try {
            // 建立连接
            conn = DriverManager.getConnection("jdbc:mysql://host:port/database", "user", "password");

            // 执行操作...

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭连接
            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

from sqlalchemy import create_engine

engine = create_engine('mysql+mysqlconnector://user:password@host/database')

# 使用连接池
with engine.connect() as connection:
    # 执行操作...

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;

import java.sql.Connection;
import java.sql.SQLException;

public class MySQLConnectionPoolExample {
    public static void main(String[] args) {
        HikariConfig config = new HikariConfig();
        config.setJdbcUrl("jdbc:mysql://host:port/database");
        config.setUsername("user");
        config.setPassword("password");

        HikariDataSource ds = new HikariDataSource(config);

        try (Connection conn = ds.getConnection()) {
            // 执行操作...
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}