(i)  I would like to know if the sending of JSON from ajax to php is correct and 

(ii) if the sending of JSON   from php to ajax is correct

(iii) and if the DOM manipulation used to load the city dropdown list at ajax is right.

<SCRIPT>

    $(Document).ready(function(){

           $("#STATECBO").click ( function(){

     var COUNTRYCOD = 1;

        $STATECOD   = STATECBO.val();

    POSTEDDATA  = {

                                       "COUNTRYCOD" : COUNTRYCOD ,

                                   "STATECOD"   : STATECOD 

           }  

    $.ajax({

               type    : "POST",

               url     : "GETCITIES.PHP",

               data    : { MYDATA : POSTEDDATA };

               dataType: "json", 

               success : function(CITIES){

            var CBOCONTROL = $(#CITYCBO );

        CBOCONTROL.empty();

    for ( N = 0; N < CITIES.length; N++ ){

                  CBOCONTROL.Append($("<OPTION></OPTION>").attr("value",CITIES[N].CITYCOD).text(CITIES[N].CITYNAM));

            };

       };

        });

   });  

    });

   

   </SCRIPT>

   

   ###################################################################

   ###################################################################

   

                   GETCITIES.PHP

   

   

      $DATA         =  $_POST['MYDATA'];

      $DATADECODE   =  json_decode( $DATA);

      $COUNTRYCOD   =  $DATADECODE["COUNTRYCOD"]; 

 $STATECOD     =  $DATADECODE["STATECOD"];  

 $CON          = mysql_connect("localhost", "root","");

 mysql_select_db( "AJAXDBF", $CON );

      $SQLCITY = " SELECT * FROM CITY WHERE COUNTRYCOD =" . $COUNTRYCOD ;

      $SQLCITY.= " WHERE   STATECOD =" . $STATECOD ;  

 $FCITY   =  mysql_query( $SQLCITY, $CON ) ;

      while ( $ROW  = mysql_fetch_array( $FCITY )){

      $CITIES = array( 

     'CITYCOD'=> $ROW["CITYCOD"],

 'CITYNAM'=> $ROW["CITYNAM"])

 }

 echo(json_encode($CITIES));

    ######################################################################

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