If the values are available in database table then the check boxes are checked when it show on the page execution time.

 
Sample code:

<?php $project_id=trim ($_GET ['project_id']); $query="select * from project_details where projectid='$project_id'"; $result=mysql_query($query,$Link); $row = mysql_fetch_assoc($result); $projectname=$row['projectname']; ?> <form name="frmEditProjectDetails" method="post" action="update_projectdetails.php?projectid=<?php echo $project_id?>" > <table align="center" id="tblprojectdetails" > <tr> <td> <h4>Edit Project Details </h4> </td> </tr> <tr> <td align="left">Project Name :</td> <td align="left"> <input type="text" name="projectname" value="<?php echo $projectname;?>"/> </td> </tr> <tr> <td align="left">Employee Id :</td> <td align="left"> <?php //For Selecting Employee ID $sqlquery="select * from employee_details "; $sqlresult=mysql_query($sqlquery,$Link); $num=mysql_num_rows($sqlresult) or $num=0; $rowno=1; while ($rowno <= $num ) { $employeeid=mysql_result($sqlresult, $rowno-1, 'employee_id'); $query="select employee_id from employee_involved_project where project_id='$project_id' and employee_id='$employeeid' "; $result=mysql_query($query); if (mysql_num_rows($result)!=0) { $checkedemployeestatus ="checked"; } else { $checkedemployeestatus =""; } ?> <tr> <td align="right"> <input type="checkbox" name="chkemployeeid[]" value="<?php echo $employeeid;?>" <?php echo $checkedemployeestatus; ?>/> </td> <td align="left"> <?php echo $employeeid;?></a></td> </tr> <?php $rowno++; } ?> </td> </tr> <?php mysql_close($Link); ?> </table> <table align="center"> <tr><td><input type="submit" name="submit" value="Edit Project Details" /> </td> </tr> </table> </form>

Sample Output