js鏁扮粍鍏冪礌鐨勬坊鍔犲拰鍒犻櫎涓鐩存瘮杈冭糠鎯戯紝浠婂ぉ緇堜簬鎵懼埌璇︾粏璇存槑鐨勮祫鏂欎簡(jiǎn)錛屽厛緇欎釜鎴戞祴璇曠殑浠g爜^-^
var arr = new Array();
arr[0] = "aaa";
arr[1] = "bbb";
arr[2] = "ccc";
//alert(arr.length);//3
arr.pop();
//alert(arr.length);//2
//alert(arr[arr.length-1]);//bbb
arr.pop();
//alert(arr[arr.length-1]);//aaa
//alert(arr.length);//1
var arr2 = new Array();
//alert(arr2.length);//0
arr2[0] = "aaa";
arr2[1] = "bbb";
//alert(arr2.length);//2
arr2.pop();
//alert(arr2.length);//1
arr2 = arr2.slice(0,arr2.length-1);
//alert(arr2.length);//0
arr2[0] = "aaa";
arr2[1] = "bbb";
arr2[2] = "ccc";
arr2 = arr2.slice(0,1);
alert(arr2.length);//1
alert(arr2[0]);//aaa
alert(arr2[1]);//undefined
shift錛氬垹闄ゅ師鏁扮粍絎竴欏癸紝騫惰繑鍥炲垹闄ゅ厓绱犵殑鍊鹼紱濡傛灉鏁扮粍涓虹┖鍒欒繑鍥?/span>undefined
var a = [1,2,3,4,5];
var b = a.shift(); //a錛歔2,3,4,5] b錛?
unshift錛氬皢鍙傛暟娣誨姞鍒板師鏁扮粍寮澶達(dá)紝騫惰繑鍥炴暟緇勭殑闀垮害
var a = [1,2,3,4,5];
var b = a.unshift(-2,-1); //a錛歔-2,-1,1,2,3,4,5] b錛?
娉細(xì)鍦?span style="font-family: 'Times New Roman';">IE6.0涓嬫祴璇曡繑鍥炲兼諱負(fù)undefined錛孎F2.0涓嬫祴璇曡繑鍥炲間負(fù)7錛屾墍浠ヨ繖涓柟娉曠殑榪斿洖鍊間笉鍙潬錛岄渶瑕佺敤榪斿洖鍊兼椂鍙敤splice浠f浛鏈柟娉曟潵浣跨敤銆?/span>
pop錛氬垹闄ゅ師鏁扮粍鏈鍚庝竴欏癸紝騫惰繑鍥炲垹闄ゅ厓绱犵殑鍊鹼紱濡傛灉鏁扮粍涓虹┖鍒欒繑鍥?span style="font-family: 'Times New Roman';">undefined
var a = [1,2,3,4,5];
var b = a.pop(); //a錛歔1,2,3,4] b錛?//涓嶇敤榪斿洖鐨勮瘽鐩存帴璋冪敤灝卞彲浠ヤ簡(jiǎn)
push錛氬皢鍙傛暟娣誨姞鍒板師鏁扮粍鏈熬錛屽茍榪斿洖鏁扮粍鐨勯暱搴?/span>
var a = [1,2,3,4,5];
var b = a.push(6,7); //a錛歔1,2,3,4,5,6,7] b錛?
concat錛氳繑鍥炰竴涓柊鏁扮粍錛屾槸灝嗗弬鏁版坊鍔犲埌鍘熸暟緇勪腑鏋勬垚鐨?/span>
var a = [1,2,3,4,5];
var b = a.concat(6,7); //a錛歔1,2,3,4,5] b錛歔1,2,3,4,5,6,7]
splice(start,deleteCount,val1,val2,...)錛?/span>浠?span style="font-family: 'Times New Roman';">start浣嶇疆寮濮嬪垹闄?span style="font-family: 'Times New Roman';">deleteCount欏癸紝騫朵粠璇ヤ綅緗搗鎻掑叆val1,val2,...
鍦ㄦ竻絀烘暟緇勬椂錛屽彧闇浼犻?span style="font-family: 'Times New Roman';">startIndex銆?/span>
濡傛灉涓嶅垹闄ゆ墍鏈夊厓绱狅紝鍐嶄紶閫?span style="font-family: 'Times New Roman';">deleteCount鍙傛暟銆?/span>
splice榪樺叿鏈夊厛鍒犻櫎鍚庢坊鍔犵殑鍔熻兘錛屽嵆鍏堝垹闄ゅ嚑涓厓绱狅紝鐒跺悗鍦ㄥ垹闄ょ殑浣嶇疆鍐嶆坊鍔犺嫢騫插厓绱狅紝鍒犻櫎涓庢坊鍔犵殑鍏冪礌鐨勪釜鏁版病鏈夊繀欏葷浉絳夛紝榪欐椂渚?span style="font-family: 'Times New Roman';">deleteCount涔熸槸瑕佺敤鍒扮殑銆?/span>
var a = [1,2,3,4,5];
var b = a.splice(2,2,7,8,9); //a錛歔1,2,7,8,9,5] b錛歔3,4]
var b = a.splice(0,1); //鍚宻hift
a.splice(0,0,-2,-1); var b = a.length;//鍚?span style="font-family: 'Times New Roman';">unshift
var b = a.splice(a.length-1,1);//鍚?span style="font-family: 'Times New Roman';">pop
a.splice(a.length,0,6,7); var b = a.length; //鍚?span style="font-family: 'Times New Roman';">push
reverse錛氬皢鏁扮粍鍙嶅簭
var a = [1,2,3,4,5];
var b = a.reverse(); //a錛歔5,4,3,2,1] b錛歔5,4,3,2,1]
sort(orderfunction)錛?/span>鎸夋寚瀹氱殑鍙傛暟瀵規(guī)暟緇勮繘琛屾帓搴?/span>
var a = [1,2,3,4,5];
var b = a.sort(); //a錛歔1,2,3,4,5] b錛歔1,2,3,4,5]
slice(start,end)錛?/span>榪斿洖浠庡師鏁扮粍涓寚瀹氬紑濮嬩笅鏍囧埌緇撴潫涓嬫爣涔嬮棿鐨勯」緇勬垚鐨勬柊鏁扮粍
var a = [1,2,3,4,5];
var b = a.slice(2,5); //a錛歔1,2,3,4,5] b錛歔3,4,5]
join(separator)錛?/span>灝嗘暟緇勭殑鍏冪礌緇勮搗涓涓瓧絎︿覆錛屼互separator涓哄垎闅旂錛岀渷鐣ョ殑璇濆垯鐢ㄩ粯璁ょ敤閫楀彿涓哄垎闅旂
var a = [1,2,3,4,5];
var b = a.join("|"); //a錛歔1,2,3,4,5] b錛?1|2|3|4|5"
鍐嶇粰涓埄鐢ㄦ暟緇勬ā鎷?span style="font-family: 'Times New Roman';">javaStringBuffer澶勭悊瀛楃涓茬殑鏂規(guī)硶錛?/span>
/**
* 瀛楃涓插鐞嗗嚱鏁?/span>
*/
function StringBuffer() {
var arr = new Array;
this.append = function(str) {
arr[arr.length] = str;
};
this.toString = function() {
return arr.join("");//鎶?span style="font-family: 'Times New Roman';">append榪涙潵鐨勬暟緇?span style="font-family: 'Times New Roman';">ping鎴愪竴涓瓧絎︿覆
};
}
浠婂ぉ鍦ㄥ簲鐢ㄤ腑紿佺劧鍙戠幇join鏄竴縐嶆妸鏁扮粍杞崲鎴愬瓧絎︿覆鐨勫ソ鏂規(guī)硶錛屾晠灝佽鎴愬璞′嬌鐢ㄤ簡(jiǎn)錛?/span>
/**
*鎶婃暟緇勮漿鎹㈡垚鐗瑰畾絎﹀彿鍒嗗壊鐨勫瓧絎︿覆
*/
function arrayToString(arr,separator) {
if(!separator) separator = "";//separator涓簄ull鍒欓粯璁や負(fù)絀?/span>
return arr.join(separator);
}
/**
* 鏌ユ壘鏁扮粍鍖呭惈鐨勫瓧絎︿覆
*/
function arrayFindString(arr,string) {
var str = arr.join("");
return str.indexOf(string);
}
濡傛灉浠呬粎鏄煡鎵炬暟鎹簱涓璶ame涓嶉噸澶嶇殑瀛楁錛屽緢瀹規(guī)槗
- SELECT min(`id`),`name`
- FROM `table`
- GROUP BY `name`;
浣嗘槸榪欐牱騫朵笉鑳藉緱鍒拌鏈夐噸澶嶅瓧孌電殑id鍊箋傦紙鍙緱鍒頒簡(jiǎn)鏈灝忕殑涓涓猧d鍊鹼級(jí)
鏌ヨ鍝簺瀛楁鏄噸澶嶇殑涔熷鏄?/p>
- SELECT `name`,count(`name`) as count
- FROM `table`
- GROUP BY `name` HAVING count(`name`) >1
- ORDER BY count DESC;
浣嗘槸瑕佷竴嬈℃煡璇㈠埌閲嶅瀛楁鐨刬d鍊鹼紝灝卞繀欏諱嬌鐢ㄥ瓙鏌ヨ浜?jiǎn)锛屼簬鏄娇鐢ㄤ笅闈㈢殑璇彞鏉ュ疄鐜癕ySQL澶ц〃閲嶅瀛楁鏌ヨ銆?/p>
- SELECT `id`,`name`
- FROM `table`
- WHERE `name` in (
- SELECT `name`
- FROM `table`
- GROUP BY `name` HAVING count(`name`) >1
- );
浣嗘槸榪欐潯璇彞鍦╩ysql涓晥鐜囧お宸紝鎰熻mysql騫舵病鏈変負(fù)瀛愭煡璇㈢敓鎴愰浂鏃惰〃銆?/p>
浜庢槸浣跨敤鍏堝緩绔嬮浂鏃惰〃
- create table `tmptable` as (
- SELECT `name`
- FROM `table`
- GROUP BY `name` HAVING count(`name`) >1
- );
鐒跺悗浣跨敤澶氳〃榪炴帴鏌ヨ
- SELECT a.`id`, a.`name`
- FROM `table` a, `tmptable` t
- WHERE a.`name` = t.`name`;
緇撴灉榪欐緇撴灉寰堝揩灝卞嚭鏉ヤ簡(jiǎn)銆?/p>
鐢?distinct鍘婚噸澶?/p>
- SELECT distinct a.`id`, a.`name`
- FROM `table` a, `tmptable` t
- WHERE a.`name` = t.`name`;