WHAT IS AJAX

IT STANDS FOR ASYNCHRONOUS JAVASCRIPT ASYNCHRONOUS XML .AJAX is widely used for real time results from server like data needed for a site showing sharebazzar news or one showing cricket scores.

It is quite easy to learn AJAX

Just simply crate a AJAX Object and call it through JAVASCRIPT

Here is a simple function to create xmlhttp object
function the_Object() {
   
    var xmlhttp;
    // This if condition for Firefox and Opera Browsers
    if (!xmlhttp && typeof XMLHttpRequest != 'undefined') {
        try  {
            xmlhttp = new XMLHttpRequest();
        }
        catch (e) {
            alert("Your browser is not supporting XMLHTTPRequest");
            xmlhttp = false;
        }
    }
    // else condition for ie
    else {
        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    return xmlhttp;
}
var request = the_Object();

THIS OBJECT THEN USED WITH  JAVASCRIPT TO PERFORM TASK

HERE IS EXAMPLE

function searchdata(){

var tosearch = document.getElementById("txtsearch").value;
var searchby = document.getElementById("selfld").value;
if(searchby=='0'){
     alert("Please select Category");
return false;
}
var url = "search.php";// PHP SCRIPT FILE
url1= url+"?tosearch="+tosearch+"&searchby="+searchby; //PASSING VARIABLE
request.open("GET", url1, true);//OPEN URL

request.onreadystatechange = function aa() {//Call a function when the state changes.
       
        if(request.readyState == 4 && request.status == 200) {
            ans=request.responseText;
            document.getElementById("test").style.visibility = 'visible';
            document.getElementById("test").innerHTML=ans;//PLACE OUTPUT
            }
}
request.send(null);
}

THIS IS HOW AJAX WORKS

How to fetch records from Mysql Databae

The important technique in php is to fetch records from the database to list the data you need to used following php functions

1. mysql_connect : to connect the mysql server with apache server
2. mysql_select_db : to connect to a particular database in the mysql server
3. mysql_query  : to fire a query in the database.
4. mysql_num_rows to find the number of records in a recordset which is derived from query fired.
5. mysql_fetch_array to fetch array from record set.
6. mysql_fetch_assoc  to fetch row from associative array.
7. mysql_fetch_row  to  fetch row from record set.
8. mysql_fetch_object  to fetch the data as object generally use to fetch large data
9. mysql_close close mysql connection   

Step by step we can use this functions to fetch data from Database 

 Using while loop


$recordset = mysql_query("select * from DBTABLE"); 
while ($record= mysql_fetch_array($recordset ) { 
                echo "user_id: ".$record["db_field_name"]."<br />\n"; // as in database
                echo "user_id: ".$record[0]."<br />\n"; // in key value as in array
                  }


This will fetch the database values from dbtable and retrieve list of particular db_field_name


Using for while loop and mysql_fetch_object
$recordset = mysql_query("select * from DBTABLE"); 


while ($record= mysql_fetch_object($recordset )) { 
         echo $record->db_field_name; 
} 

Using for loop
$record= mysql_fetch_array($recordset );
$count=count($record) ;
for($i = 0;$i< $count ; $i ++)
{ 
                 echo "user_id: ".$record[$i]["db_field_name"]."<br />\n"; // as in database
}
 we will go through other function later...