Question

我正在尝试在nodejs中编写一个带有两个查询的api，从查询中获取的数据应该合并，并且应该从服务器发送一个json响应。我尝试了以下方式，但不知怎的，我得到了空值。

app.get('/api/task_details',function(req,res,err){
    var sql = "select * from users inner join user_level_task on users.user_id=user_level_task.user_id inner join tasks on tasks.task_id = user_level_task.task_id where task_name = 'game'";
    var sql2="select * from tasks where task_name='game'";
    var res1 = '',res2='';
    db.select(sql,function(err,data){
        var res1 =data;
    })

     db.select(sql2,function(err,data){
        var res2 = data;
    })

    res.end(JSON.stringify(res1+res2));
})

Answer 1

您的代码应该是这样的。

app.get('/api/task_details',function(req,res,err){
    var sql = "select * from users inner join user_level_task on users.user_id=user_level_task.user_id inner join tasks on tasks.task_id = user_level_task.task_id where task_name = 'game'";
    var sql2="select * from tasks where task_name='game'";
    var res1 = {}
    db.select(sql,function(err,data1){
        db.select(sql2,function(err,data2){
        res1.data1= data1;
        res1.data2=data2;
        res.end(JSON.stringify(res1));
    })
    })

})

Answer 2

试试这段代码

const mysql = require('mysql');
const express = require('express');
const app = express();
var async = require('async');
const connection = mysql.createConnection({
    host: 'localhost',
    user: 'xxxx',
    password: 'xxxx',
    database: 'Name of the DataBase'
});

connection.connect();
app.get('/api/task_details', (req, res) => {
async.parallel([
function (callback)
{ 
setTimeout(function(){
connection.query(SELECT * FROM users inner join user_level_task on users.user_id=user_level_task.user_id inner join tasks on tasks.task_id = user_level_task.task_id where task_name = 'game', (error, data1) => {
        if(error) => {
            console.log(error)
       } 
        callback(null,data1);
    });
   },200);
}

function (callback)
{ 
setTimeout(function(){
connection.query(SELECT * FROM tasks where task_name='game',(error, data2) => {
        if(error) => {
            console.log(error)
        }
        callback(null,data2);
    });
},100);
    }
    ],
    function(err,results){
        res.end(JSON.stringify(results));
    });

});

希望这会对你有所帮助

单个api中的多个查询

2 个答案: