Как написать функцию на js для работы с mysql

Question

Вот код

const mysql      = require('mysql');
const connection = mysql.createConnection({host: "host", user: "user", database: "database", password: "password"});

function select__sql(sql){
        connection.connect();
        try{
                connection.query(sql, result => {
                        return 'This is result: ', result;
                        });
        } finally {
                connection.end();
        }
}

console.log(select__sql('SELECT * FROM tablename'));

И я не понимаю почему совершается вывод indefind, хотя по теории должен совершиться вывод массива с данными

Новая версия кода

function select__sql(sql){
        connection.connect();
        try{
                var results = connection.query(sql, function (error, results, fields){
                });               
                return results;
        } finally {
                connection.end();
        }
}

console.log(select__sql('SELECT * FROM tablename'));

И теперь у меня вот такой вывод

Query {
  _events:
   [Object: null prototype] {
     error: [Function],
     packet: [Function],
     timeout: [Function],
     end: [Function] },
  _eventsCount: 4,
  _maxListeners: undefined,
  _callback: [Function],
  _callSite:
   Error
       at Protocol._enqueue (/home/v1nc3nt_one1ll/node_modules/mysql/lib/protocol/Protocol.js:144:48)
       at Connection.query (/home/v1nc3nt_one1ll/node_modules/mysql/lib/Connection.js:198:25)
       at select__sql (/home/v1nc3nt_one1ll/Desktop/Template by/sql.js:49:42)
       at Object.<anonymous> (/home/v1nc3nt_one1ll/Desktop/Template by/sql.js:58:13)
       at Module._compile (internal/modules/cjs/loader.js:778:30)
       at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
       at Module.load (internal/modules/cjs/loader.js:653:32)
       at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
       at Function.Module._load (internal/modules/cjs/loader.js:585:3)
       at Function.Module.runMain (internal/modules/cjs/loader.js:831:12),
  _ended: false,
  _timeout: undefined,
  _timer: Timer { _object: [Circular], _timeout: null },
  sql: 'SELECT * FROM tablename',
  values: undefined,
  typeCast: true,
  nestTables: false,
  _resultSet: null,
  _results: [],
  _fields: [],
  _index: 0,
  _loadError: null,
  _connection:
   Connection {
     _events: [Object: null prototype] {},
     _eventsCount: 0,
     _maxListeners: undefined,
     config:
      ConnectionConfig {
        host: 'localhost',
        port: 3306,
        localAddress: undefined,
        socketPath: undefined,
        user: 'user',
        password: 'password',
        database: 'database',
        connectTimeout: 10000,
        insecureAuth: false,
        supportBigNumbers: false,
        bigNumberStrings: false,
        dateStrings: false,
        debug: undefined,
        trace: true,
        stringifyObjects: false,
        timezone: 'local',
        flags: '',
        queryFormat: undefined,
        pool: undefined,
        ssl: false,
        localInfile: true,
        multipleStatements: false,
        typeCast: true,
        maxPacketSize: 0,
        charsetNumber: 33,
        clientFlags: 455631 },
     _socket:
      Socket {
        connecting: true,
        _hadError: false,
        _handle: [TCP],
        _parent: null,
        _host: 'localhost',
        _readableState: [ReadableState],
        readable: false,
        _events: [Object],
        _eventsCount: 5,
        _maxListeners: undefined,
        _writableState: [WritableState],
        writable: true,
        allowHalfOpen: false,
        _sockname: null,
        _pendingData: null,
        _pendingEncoding: '',
        server: null,
        _server: null,
        timeout: 10000,
        [Symbol(asyncId)]: 5,
        [Symbol(lastWriteQueueSize)]: 0,
        [Symbol(timeout)]:
         Timeout {
           _called: false,
           _idleTimeout: 10000,
           _idlePrev: [TimersList],
           _idleNext: [TimersList],
           _idleStart: 723,
           _onTimeout: [Function: bound ],
           _timerArgs: undefined,
           _repeat: null,
           _destroyed: false,
           [Symbol(unrefed)]: true,
           [Symbol(asyncId)]: 9,
           [Symbol(triggerId)]: 1 },
        [Symbol(kBytesRead)]: 0,
        [Symbol(kBytesWritten)]: 0 },
     _protocol:
      Protocol {
        _events: [Object],
        _eventsCount: 7,
        _maxListeners: undefined,
        readable: true,
        writable: true,
        _config: [ConnectionConfig],
        _connection: [Circular],
        _callback: null,
        _fatalError: null,
        _quitSequence: [Quit],
        _handshake: true,
        _handshaked: false,
        _ended: false,
        _destroyed: false,
        _queue: [Array],
        _handshakeInitializationPacket: null,
        _parser: [Parser] },
     _connectCalled: true,
     state: 'disconnected',
     threadId: null } }

Даже здесь ничего мне не помогло

Answer 1

const mysql = require('mysql');

const connection = mysql.createConnection({
  host: "host",
  user: "user",
  database: "database",
  password: "password",
});

connection.connect();

const select__sql = (sql) => new Promise((resolve) => {
  connection.query((sql, result) => {
    resolve(result);
  });
});

const getData = async () => {
  console.log(await select__sql('SELECT * FROM tablename'));
};

getData();

Вот так, по простому если. Ну проверки на ошибки нужны и прочие прелести.

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Как написать функцию на js для работы с mysql

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