因此,我想从sql数据库(特别是sqlite)查询一些数据,并将结果放入数组中。但是,它似乎不起作用,我只得到一个空数组。我就是这么做的:
var boards = []; // init the boards array
const sqlite = require('sqlite3').verbose(); // init sqlite
var db = new sqlite.Database("database.db"); // init the database
// the query
db.all(`select * from boards;`,(
我有以下几点:
class User < ActiveRecord::Base
before_update :guest_upgrade
def guest_upgrade
# If the user changed their email that means they were a guest, and are no longer.
# Likely triggered from the Registrations#Update controller
if self.email_changed?
self.guest = false
我使用MS Access进行查询,并要求用户输入(以列表格式)。如果我按如下方式运行该查询,它将工作:
WHERE var in (1,2,3)
但是,如果我在提示用户输入它,它就不能工作(还有其他语法吗?)
WHERE var in ([Enter list:])
如果没有必要,我宁愿不创建组合框表单/列表等等。
对于以回调函数为参数的函数,我们传递一个函数,然后在包含的函数中局部调用该函数。现在,回调函数为其执行创建一个闭包。但是这个闭包不能访问包含函数属性。
下面是一个小测试示例来说明这个问题:
// Closure does NOT have access to 'private_id'
function getUserData(firstName, lastName, gender, callback) {
var fullName = firstName + " " + lastName;
var private_id = '1735HK
那段代码是怎么回事
var start = new Date();
setTimeout(function() {
var end = new Date();
console.log('Time elapsed with func1:',end - start, 'ms');
}, 500);
setTimeout(function() {
var end = new Date();
console.log('Time elapsed with func2:',end - start, 'ms'