Nodejs mysql服务器关闭连接

Question

我正在尝试使用 MySQL 节点库进行查询，每次尝试连接时，我都会得到以下信息：

Error: Connection lost: The server closed the connection.
    at Protocol.end (C:\Users\ahmedm\WebstormProjects\webSocketTot\newMYSQL\node_modules\mysql\lib\protocol\Protocol.js:112:13)
    at TLSSocket.onend (_stream_readable.js:681:10)
    at Object.onceWrapper (events.js:421:28)
    at TLSSocket.emit (events.js:327:22)
    at endReadableNT (_stream_readable.js:1220:12)
    at processTicksAndRejections (internal/process/task_queues.js:84:21)
    --------------------
    at Protocol._enqueue (C:\Users\ahmedm\WebstormProjects\webSocketTot\newMYSQL\node_modules\mysql\lib\protocol\Protocol.js:144
:48)
    at Protocol.handshake (C:\Users\ahmedm\WebstormProjects\webSocketTot\newMYSQL\node_modules\mysql\lib\protocol\Protocol.js:51
:23)
    at PoolConnection.connect (C:\Users\ahmedm\WebstormProjects\webSocketTot\newMYSQL\node_modules\mysql\lib\Connection.js:116:1
8)
    at Pool.getConnection (C:\Users\ahmedm\WebstormProjects\webSocketTot\newMYSQL\node_modules\mysql\lib\Pool.js:48:16)
    at query (C:\Users\ahmedm\WebstormProjects\webSocketTot\newMYSQL\mysql.js:20:10)
    at Object.<anonymous> (C:\Users\ahmedm\WebstormProjects\webSocketTot\newMYSQL\mysql.js:31:1)
    at Module._compile (internal/modules/cjs/loader.js:1137:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)
    at Module.load (internal/modules/cjs/loader.js:985:32)
    at Function.Module._load (internal/modules/cjs/loader.js:878:14) {
  fatal: true,
  code: 'PROTOCOL_CONNECTION_LOST'
}

代码：

const mysql_config = {// Connection parameters
    host: "********",
    user: "********",
    password: "********",
    database: "********",
    ssl:sslOptions
};

var pool = mysql.createPool(mysql_config);

var query = function(sql,callback) {
    pool.getConnection(function (err, conn) {
        if (err) {
            callback(err, null);
        } else {
            conn.query(sql, function (err, results) {
                callback(err, results);
            });
            conn.release();
        }
    });
}
query('select * from *****',function (err,res){
    console.log(err)
})