jquery-json example check userid user id had create or not

       s="tableRead?     db=erp&table=USER&fields=login_id&key=login_id&value='"+s1+"'&format=S&callback=?";


s="tableRead?"+
"db=erp&table=USER&"+
"fields=login_id&"+
"key=login_id&"+
"value='"+s4+"'&"+
"where= where login_id:`"+s4+"` and db: `"+s5+"` &" +
"format=S&callback=?";

$.getJSON(s,
function(data) {
if (data[0]){
$("#dialog").dialog( "open" );
$("#dialog").dialog('option', 'title', 'User Add  Message');
$("#dialog p").html("This user account had created !!");
return false;
}
}
)