如何取消选中该复选框

How to uncheck the checked box if another one is checked.

Could someone help.

Thanks.

<?php

//limit for number of categories displayed per page
$limit = 4;

$categoriesNum= mysql_query("SELECT COUNT('categoryTopic') FROM categories");   

//number of current page
$page =(isset($_GET['page']))? (int) $_GET['page'] :1;

//calculate the current page number 
$begin =($page - 1)* $limit; 

//number of pages needed. 
$pagesCount =ceil(mysql_result ($categoriesNum,0)/$limit);

//Query up all the Categories with setting the Limit 
$CategoryQuery = mysql_query ("SELECT categoryTopic From categories ORDER BY categoryTopic LIMIT $begin, $limit");

//Place all categories in an array then loop through it displaying them one by one
while ($query_rows = mysql_fetch_assoc($CategoryQuery))
{

    $category =$query_rows['categoryTopic'];  
    //echo $category; 
    //query all the subcategories that the current category has 
    $Sub = mysql_query ("SELECT categoryTopic FROM subcategories WHERE categoryTopic='$category'");             
    $Count = mysql_num_rows ($Sub); 

    echo  '<table width="85%" border="1"  cellpadding="0"; cellspacing="0" align="center">

    <tr>        
        <th width="23%" height="44" scope="col" align="left"> '.$query_rows['categoryTopic'].' <br><br><br></th>
        <th width="24%" scope="col">'.$Count.'</th>
        <th width="25%" scope="col"> 0 </th>
        <th width="28%" scope="col"> <form  name = "choose">
        <label><input type="checkbox" id ="check" value= '.$category.' onchange="handleChange(this);"></label>
    </tr>
</table>';  
}
?> 

<script type="text/jscript">
//this funciton will be called when user checks a check box. 

function handleChange(cb) {
//get the selected category 
var category = cb.value;

if another one gets selected I get the value of the new one but two boxes are checked at the same time.

Don't use checkboxes, use radio buttons, and give them all the same name.

Use a radio button?

<input type="radio" name="NAME" />

Where NAME is the same across all the radio buttons that you want to affect each other.

Side-note: Your current code is invalid because it produces multiple elements with the same ID (check).

If you only want one to be checked at a time then radio buttons would seem a better choice, although if you want one or zero at a time then checkboxes are fine.

Your code is currently producing invalid html because it gives the same id to each checkbox. Also you seem to be creating opening <form> tags on each row without matching </form> tags.

If you give each checkbox a common class attribute:

<input type="checkbox" class="check" value= '.$category.' onchange="handleChange(this);">

...then your JS can use .getElementsByClassName() to process them all and uncheck all but the one just checked:

function handleChange(cb) {
    var cbs = document.getElementsByClassName("check");
    for (var i = 0; i < cbs.length; i++)
        if (cbs[i] != cb)
            cbs[i].checked = false;
}

Demo: http://jsfiddle.net/33Gqu/

Note: for the chosen value to be submitted you will need to give the checkboxes a name attribute - unlike id, name can be repeated for multiple elements.