Inserting data of text field into database and printing into table by fetching from database

<?php
mysql_connect("localhost","root","");
mysql_select_db("vikash");
$sql="select * from employee";

?>
<form>
NAME   <input type="text" name="t1" ><br>
AGE    <input type="text" name="t2" ><br>
SALARY <input type="text" name="t3" ><br>
       <input type="submit" name="s1"><br>
</form>
<?php
if(isset($_REQUEST['s1']))
{
$sql1="insert into employee(name,age,salary) values(".$_REQUEST['t1'].",
".$_REQUEST['t2'].",".$_REQUEST['t3'].")";
if(mysql_query($sql1))
{
echo "inserted successfully";
}
}?>
<table border=1>
<tr><td>NAME</td><td>AGE</td><td>SALARY</td></tr>
<?php
if($dd=mysql_query($sql))
{
while($DD=mysql_fetch_array($dd))
{
echo "<tr><td>".$DD['name']."</td>,<td>".$DD['age']."</td>,<td>".$DD['salary']."</td></tr>";
}}
?>
</table>