Question

我的.js文件包含以下代码：

var mysql = require('mysql');
var connection = mysql.createConnection({
host: 'localhost',
user: 'root',
password: 'password',
database: 'databasename'});

function select(id,tablename){
connection.connect();
connection.query('select ' +tablename+'.property from databasename.'+tablename+' where id = '+id, function(err,result){
var string=JSON.stringify(result[0].property);
// alert(string); or console.log(string); 
});
connection.end();
}

// function go(){select(3,"tablename");} or select(3,"tablename");

从button.onClick（）调用function.go（）。当我通过＆＃34;节点filename.js＆＃34;从控制台运行它时它工作正常并显示正确的数据，但它不能从button.onClick（）工作。

我做错了什么？

Answer 1

你的代码错了。

你写过

var mysql = require(‘mysql'); var connection = mysql.createConnection({host: ‘localhost';user: 'root',password: 'password',database: ‘databasename'});function select(id,tablename){connection.connect();connection.query('select ' +tablename+'.property from databasename.'+tablename+' where id = '+id, function(err,result) {var string=JSON.stringify(result[0].property);/* alert(string); or console.log(string); */});

应该是

var mysql = require('mysql'); var connection = mysql.createConnection({host: 'localhost';user: 'root',password: 'password',database: 'databasename'});function select(id,tablename){connection.connect();connection.query('select ' +tablename+'.property from databasename.'+tablename+' where id = '+id, function(err,result) {var string=JSON.stringify(result[0].property);/* alert(string); or console.log(string); */});

在许多地方，您已使用‘开始使用'结尾的字符串，这可能会导致问题。

Answer 2

您应该使用单引号或双引号来包含字符串。您使用了`而不是' 在主持人之后删除分号：＆＃39; localhost＆＃39;。应该有一个逗号而不是分号

你的代码应该是这样的

 var connection = mysql.createConnection({host:'localhost',user:'root',password:'password',database: 'databasename'});


function select(id,tablename){

  connection.connect();
  connection.query('select ' +tablename+'.property from databasename.'+tablename+' where id = '+id, function(err,result) {
    var string=JSON.stringify(result[0].property);/* alert(string); or console.log(string); */

  });
}

Answer 3

我认为你混合同步和异步。你需要回调查询

var mysql = require('mysql');
var connection = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: 'password',
    database: 'databasename'
});

function select(id, tablename, callback){
    connection.connect();
    connection.query(`SELECT ${tablename}.property from databasename.${tablename} where id = ?`, [id], callback);
    connection.end();
}

function go () {
    select(3, "tablename", function (err, result) {
        // mysql response
    });
}

mysql的node.js驱动程序在控制台中工作，但在实际代码中不起作用

3 个答案: