sql - how do I use a string returned as an ajax response to assign to a php variable -

i select option drop down menu(id="field"), , on basis of value wish generate drop down menu, use ajax retrieve value of field1 input. function is:

function showbranches(degree) {   var xmlhttp=false;   if (window.xmlhttprequest)    {// code ie7+, firefox, chrome, opera, safari      xmlhttp=new xmlhttprequest();    }   else    {// code ie6, ie5      xmlhttp=new activexobject("microsoft.xmlhttp");    }    xmlhttp.open("post","sors/sendegree.php?degree="+degree,true);   xmlhttp.onreadystatechange = function(){    if (xmlhttp.readystate==4 && xmlhttp.status == 200)   {       document.getelementbyid('br').innerhtml=xmlhttp.responsetext;    }    }  xmlhttp.send(null);  }   

code in sendegree.php file simply

<?php echo $_request['degree']; ?> 

now try receive string returned ajax code php variable using statement:

<?php   $state="<span id=\"br\"></span>";    echo $state; ?> 

now problem is, first statement echo works fine, not able use $state variable in sql query below

$get_cty=mysql_query("select * abc city='$state'")or die(mysql_error());  

you need concatenate variable

try this

$get_cty=mysql_query("select * abc city='".$state."'") or die(mysql_error()); 

how learned in college whenever needed variable value in query added '".."' after equals sign put variable in middle.

hope helps.