Ajax Asynchronous request PHP data, Ajax asynchronous php_php Tutorial

Ajax asynchronously requests PHP data, Ajax asynchronous PHP

Source: http://www.ido321.com/1138.html

Received a teacher's homework, the realization of the layout

If the department ID is entered, the department name only shows the corresponding ID, if there is no input, then display all, and then according to the name of the Department of I, in the section of the text box automatically display the department name of the major section. For example: Cardiovascular medicine was selected, and the Department of Internal Medicine was shown in its own major.

The main code is as follows:

Request department based on ID

function Showhint (str) {    var xmlhttp;    if (Window. XMLHttpRequest)     {//ie7+, Firefox, Chrome, Opera, Safari        xmlhttp=new XMLHttpRequest ();     }       Else     {//IE6, IE5        xmlhttp=new ActiveXObject ("Microsoft.XMLHTTP");     }     xmlhttp.onreadystatechange=function()    {       if (xmlhttp.readystate==4 && xmlhttp.status==200)      {        document.getElementById ("Txthint"). Innerhtml=xmlhttp.responsetext;      }  }    Xmlhttp.open ("GET","keshi.php?q="+str,true);    Xmlhttp.send ();}

keshi.php:

/  
    * Prevent malicious calls *
  /Define"TEST",' Test ');//Introduction fileinclude_once ' mysql.func.php ';//Database initializationConnectmysql (); Selectdb (); Setzifuji ();//Get the Q parameter from the URL$q =$_get["Q"];//If q is a numeric or numeric stringif(Is_numeric ($q))    {$q = Intval ($q); $hint =""; $resultDKQ = Querydb ("SELECT name from Table_dake where id= $q"); $hint =' Department Name:'; while (!! $rowDKQ = Fetchassoc ($resultDKQ)) {$hint. = '< span="">]. '      > '; $resultKSQ = Querydb ("Select Table_dake.id,table_keshi.sid,table_keshi.name from Table_dake,table_keshi where Table_      Dake.name= ' {$rowDKQ [' name ']} ' and Table_keshi.sid=table_dake.id '); while (!! $rowKSQ = Fetchassoc ($resultKSQ)) {$hint. = '' Name ']. '      > '. $rowKSQ [' name ']. ';    } $hint. = ';    }}//is not a number else {$resultDK = Querydb ("Select Table_dake.name from Table_dake"); $hint = ' Department Name:'; while(!! $rowDK = Fetchassoc ($resultDK)) {$hint. ='< span="">].      ' > '; $resultKS = Querydb ("Select Table_dake.id,table_keshi.sid,table_keshi.name from Table_dake,table_keshi where      Table_dake.name= ' {$rowDK [' name ']} ' and Table_keshi.sid=table_dake.id ');  while (!! $rowKS = Fetchassoc ($resultKS)) {$hint. = '' Name ']. ' >'. $rowKS [' name '].      ''; } $hint. = "; }} $response = $hint;//Output ResponseEcho$response;? >

Effect:

ID not entered as, enter ID in:

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After committing asynchronously with Ajax, how does PHP write the code to return the results of the processing to the client

Directly echo ' String ' in the S-end, or EXIT (Json_encode (array)); All right,

The Async of Ajax

Each request is not a problem, but there must be a delay in each request. The problem with Async is that there are delays, there is no question of receiving the return value, and the return value is definitely where you wrote it wrong.

At the same time you this situation my comparison suggested that the data are requested at a time, there is a client side, and then as necessary to display it.

Hope to help you!

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