我想使用next和previous按钮使用php从数据库中获取数据

Question

I am making a exam portal in which i have option conducting exam/quiz. Now i have added 2 buttons namely Next and Previous . I wanted to fetch Question and its option on button Click. My database has following structure: Question(qid,question,option1,option2,option3,option4,right_option) What I am tryin to do:

<input id="first" type="button" value="NEXT" onClick = "show_next()">
<input id="second" type="button" value="PREV" onClick = "show_prev()">

<script>
function show_next()
{
<?php 
$question_no; //my global php variable to keep track of question id
$question_no = $question_no + 1; 
show_question($question_no); //php function which shows data according to question no 
?>
 }
function show_prev()
{
<?php 
if($question_no>0)
{
$question_no = $question_no-1;
show_question();
}
else
{
?>
alert("Wrong Operation");
<?php
}
?>
}
</script>

I am new to php and javascript, please suggest the correct method and if possible coding snippet for my question

Answer 1

Use jQuery/AJAX. All you have to do is manage Offset and Limit dynamically. e.g.

lets consider you are showing 1 question at a time and its options.

your html file will be.

<input id="first" type="button" value="NEXT" onClick = "show_next()">
<input id="second" type="button" value="PREV" onClick = "show_prev()">
<input id="offset" type="hidden" value="0">

In your javascript file

function show_next()
{
  var offset=$('#offset').val();
  $.post('GetQuestion.php',{offset:offset},function(data){
    $('#question_answer').html(data);
    $('#offset').attr('value',offset+1);

  })
}

function show_prev()
{
  var offset=$('#offset').val();
  $.post('GetQuestion.php',{offset:offset},function(data){
    $('#question_answer').html(data);
    $('#offset').attr('value',offset-1);

  })
}

In your GetQuestion.php file you can access offset value using $_POST. All you have to do is use that value in your query.

mysql_query("SELECT * FROM questions LIMIT ".$_POST['offset'].",1");

echo your query result in php file so that it could be available to var data in javascript.