select * from teacher
join school on teacher.id = school.id
join course on teacher.id = course.id
where course.name= "english"
分解后
select * from course where name = "english"
select * from school where course_id = 1
select * from teacher where school_id in (1,2,3)
update tableA as ca inner join tableB as cb set ca.thumbs=cb.thumbs where cb.courseid=1; 24.php后期静态绑定
class A {
public static function get_self() {
return new self();
}
public static function get_static() {
return new static();
}
}
class B extends A {}
get_class(B::get_self());//A
get_class(B::get_static()) //B
get_class(A::get_static());//A
var regex_num_set = /&#(d+);/g;
var str = "Here is some text: 每日一色|蓝白~"
str2 = str.replace(regex_num_set, function(_, $1) {
return String.fromCharCode($1);
});//"Here is some text: 每日一色|蓝白~"
var arr=[1,,3];//第2个位置为空位置
var result=arr.map(function(x){
console.log(x);
return x + 1;//2,undefined,4
});
arr[1]=undefined;//第2个位置为非空位置，有值undefined
result=arr.map(function(x){
console.log(x);
return x + 1;//2,NaN,4
});
setTimeout传入参数
for(var i = 0; i循环中promise
var userIds = ["aaa", "bbb", "ccc"];
//这里getUserById返回的是Promise
var promises = arr.map(userIds => getUserById(userId));
Promise
.all(promises)
.then(function(users) {
console.log(users); //这里就是users的列表了
});
window.onload=function(){
var li=document.getElementsByTagName("li");
for(var j=0;j判断一个json对象中是否含有某个key
function find (obj, key) {
if (! typeof obj === "object") return false;
if (key in obj) return true;
for (var k in obj) if find(obj[k], key) return true;
return false;
}
function getRangeIndex(scrollTop) {
var i=0;
ranges = [2,3,6,22,88];
for (;i快速生成一个数组，数组的元素是前N个自然数
let f = length => Array.from({length}).map((v,k) => k);
let f = length => [...Array.from({length}).keys()]
let fn = len => Object.keys(new Array(len + 1).join(","))
每取10行放到一个新的文件中
with open("file.txt") as reader, open("newfile.txt", "w") as writer:
for index, line in enumerate(reader):
if index % 10 == 0:
writer.write(line)
$str=" Controllable Eu valence for photoluminescence tuning in apatite-typed";
//pC:所有的unicode“other” pZ:所有的unicode“separator” ,所有空格和不可见字符
echo $str = preg_replace("/^[pZpC]+|[pZpC]+$/u","",$str);//Controllable Eu valence for photoluminescence tuning in apatite-typed
for (var i = 0; i < 6; i++) {
// do 同步执行，里面的 i 是 0
do(i).then(function() {
// another 异步执行，此时 i 已经是循环后的6
another(i)
})
}
//使用闭包保存变量的方式来解决
for (var i = 0; i < 6; i++) {
// 立即执行函数作闭包，保存变量i为index
(function(index) {
do(index).then(function() {
another(index);
})
})(i)
}
按照字母和数字的顺序进行排序
var arr = ["A1","A2","A100","A7","B2","A10","A14","B12","C1","C10","C5"]
arr.sort(function(a, b) {
var ret = a.charCodeAt(0) - b.charCodeAt(0); // 首字母处理
if (ret == 0) {
ret = +a.slice(1) - +b.slice(1); // 数字处理
}
return ret;//["A1", "A2", "A7", "A10", "A14", "A100", "B2", "B12", "C1", "C5", "C10"]
});
JSON.parse转换报错
var getValue = function (objStr) {
return new Function("return " + objStr)()
}
// 调用
var res1 = getValue("{"foo" : 1, }")//Object {foo: 1}
JSON.parse(res1);
javascript正则替换
var str = "abc{xdf}efg{dfg}ijk{232}";
var arr = ["d", "h", "l"];
var result = str.match(/{.*?}/g);
for (var i = 0; i < result.length; i++) {
str = str.replace(result[i], arr[i])
}
console.log(str);
//abcdefghijkl
javascript闭包
function Score(){
this.scores = [];
}
Score.prototype.add = function(score){
this.scores.push(score);
};
Score.prototype.showAverage = function(){
let sum = this.scores.reduce(function(pre,cur){
return pre+cur;
});
console.log(sum*1.0/this.scores.length);
};
let scores = [90,80,70];
let score1 = new Score();
scores.forEach(score1.add);//scores.forEach(score1.add.bind(score1));
scores.forEach(function(score) {
score1.add(score);
});
score1.showAverage();
javascript array reduce()
arr.reduce(function (pre, cur, index) {
if (index >= 3) {
return pre;
}
return pre + cur;
}, initVal);
javascript 汉字占2字节
function getLength(str) {
return str.replace(/[^ -~]/g, "AA").length;
}
function limitMaxLength(str, maxLength) {
var result = [];
for (var i = 0; i < maxLength; i++) {
var char = str[i]
if (/[^ -~]/.test(char))
maxLength--;
result.push(char);
}
return result.join("");
}
function getType(value){ //基本上可以返回所有的类型，不论你是自定义还是原生
return Object.prototype.toString.call(value).match(/s{1}(w+)/)[1];
}
let obj = new Object();
console.log(getType(obj)); //"Object"
moment.js时间处理
var a = moment([2016, 0, 15]);
var b = moment([2016, 7, 31]);
var diff = b.diff(a, "months");
var diffMonths = Array
.apply([], new Array(diff + 1))
.map(function(item, index) {
return a.clone().add(index, "month").format("YYYY-MM");
});
console.log(diffMonths);//["2016-01", "2016-02", "2016-03", "2016-04", "2016-05", "2016-06", "2016-07"]
test表的结构
id test1 test2
1 a 1
2 a 2
3 a 3
4 a 1
5 b 1
6 b 2
7 b 3
8 b 2
select distinct test1 from test
test1
a
b
select distinct test1, id from test
test1 id
a 1
a 2
a 3
a 4
b 5
b 6
b 7
b 8
SELECT id, group_concat( DISTINCT test1 ) t FROM test GROUP BY test1
id t
1 a
5 b
new Date(2016,1,31) > new Date(2016, 2, 1)//true
//month 从 0 开始算 new Date(2016,1,31) == 2016 年 2 月 31 日 然而 2 月只有 29 天 so
new Date(2016,1,31) == 2016 年 3 月 2 日
new Date(2016,1,30) > new Date(2016, 2, 1)//false
javascript lastIndex
function filtrate() {
var newArr = [], reg = /^s*$/g,
str = "baidu,google, , ,baidu,google,bg";
arr = str.split(",");
for (var i = 0; i < arr.length; i++) {
//var reg = /^s*$/g;
if (!reg.test(arr[i])) {
newArr.push(arr[i]);
}
}
return newArr;//["baidu", "google", " ", "baidu", "google", "bg"]
}
function filtrate2() {
var newArr = [], reg = /^s*$/g,
str = "baidu,google, , ,baidu,google,bg";
arr = str.split(",");
for (var i = 0; i < arr.length; i++) {
var reg = /^s*$/g;
if (!reg.test(arr[i])) {
newArr.push(arr[i]);
}
}
return newArr; //["baidu", "google", "baidu", "google", "bg"]
}
微信浏览器禁止页面下拉查看网址
var overscroll = function(el) {
el.addEventListener("touchstart", function() {
var top = el.scrollTop
, totalScroll = el.scrollHeight
, currentScroll = top + el.offsetHeight;
//If we"re at the top or the bottom of the containers
//scroll, push up or down one pixel.
//
//this prevents the scroll from "passing through" to
//the body.
if(top === 0) {
el.scrollTop = 1;
} else if(currentScroll === totalScroll) {
el.scrollTop = top - 1;
}
});
el.addEventListener("touchmove", function(evt) {
//if the content is actually scrollable, i.e. the content is long enough
//that scrolling can occur
if(el.offsetHeight < el.scrollHeight)
evt._isScroller = true;
});
}
overscroll(document.querySelector(".scroll"));
document.body.addEventListener("touchmove", function(evt) {
//In this case, the default behavior is scrolling the body, which
//would result in an overflow. Since we don"t want that, we preventDefault.
if(!evt._isScroller) {
evt.preventDefault();
}
});
$string="2string";
switch($string)
{
case (string) 1:
echo "this is 1";
break;
case (string) 2:
echo "this is 2";
break;
case "2string":
echo "this is a string";
break;
}
输出调试信息
function log(msg){
var $body = document.querySelector("body");
if( !$body.querySelector(".info_wz_852") ){
$body.innerHTML += "";
}
var $info = $body.querySelector(".info_wz_852");
var date = new Date(),
minute = ("00"+date.getMinutes()).slice(-2),
second = ("00"+date.getSeconds()).slice(-2);
try{
throw new Error();
}catch(e){
var loc = (e.stack.replace(/Error
/).split(/
/)[1]).replace(/^(s|u00A0)+/,"").replace(/(s|u00A0)+$/,"");
// var arr = loc.split(":"),
// col = parseInt(arr.pop()),
// line = parseInt(arr.pop());
$info.innerHTML += "
["+minute+":"+second+"] "+loc+"
"+msg+"
";
}
}
对象数组互转方法
/**
* 数组转换对象
*
* @param $arr 数组
* @return object|void
*/
public function arrayToObject($arr)
{
if (gettype($arr) != "array") return;
foreach ($arr as $k => $v) {
if (gettype($v) == "array" || getType($v) == "object")
$e[$k] = (object)$this->arrayToObject($v);
}
return (object)$e;
}
/**
* 对象转换数组
*
* @param $e StdClass对象实例
* @return array|void
*/
public function objectToArray($s)
{
$s = (array)$s;
foreach ($s as $k => $v) {
if (gettype($v) == "resource") return;
if (gettype($v) == "object" || gettype($v) == "array")
$e[$k] = (array)$this->objectToArray($v);
}
return $e;
}
javascript数组随机
Array.prototype.shuffle = function(n) {
var len = this.length , num = n?Math.min(n,len):len,arr = this.slice(0)
arr.sort(function(a,b){
return Math.random()-0.5
})
return arr.slice(0,num-1)
}
