如何在node.js中关闭数据库连接？

当我关闭数据库连接时node.js我收到这个错误

Cannot enqueue Query after invoking quit.

这是我的code

socket.on('adminConnect', function (email) {
    connection = mysql.createConnection(db_config); // db_config has all details of database
    connection.connect(); // no problem in connection
    connection.query("SELECT id FROM user WHERE  email = '" + email + "' ", function (err, results, fields) {
        if (err) throw err;
        if (results[0]) {
            // Some code
            connection.end(); // its giving error "Cannot enqueue Query after invoking quit."
        } else {
            console.log("no id");
        }
    });
});

一般来说，您会重复使用连接，而不是一直打开/关闭。

要回答你的问题，方法如下：

connection.end();

尝试将该行放在回调之外，因为所有查询都必须在结束连接之前完成，因此您是安全的：

connection.query(.......);
connection.end();

那么你的代码将是：

socket.on('adminConnect', function (email) {
    connection = mysql.createConnection(db_config); // db_config has all details of database
    connection.connect(); // no problem in connection
    connection.query("SELECT id FROM user WHERE  email = '" + email + "' ", function (err, results, fields) {
        if (err) throw err;
        if (results[0]) {
            // Some code
        } else {
            console.log("no id");
        }
    });
    connection.end();
});