Simple examples of PHP MySql addition, deletion, modification and search

<?php
  $con=@mysql_connect('localhost','root','root');//Connect the database  mysql_select_db('test',$con);//Select a database  $userInfo=mysql_query("select * from user",$con);//Create SQL statement  echo "<table>";
  while($row=mysql_fetch_assoc($userInfo))//Get the data of each row of the result set  {
    echo "<tr>";
    echo "<td>";
    echo $row['id'];//Get the id in the row    echo "</td>";
    echo "<td>";
    echo $row['username'];
    echo "</td>";
    echo "<td>";
    echo $row['password'];
    echo "</td>";
    echo "</tr>";
  }
  echo "</table>";
  mysql_free_result($userInfo);//Release the result set  mysql_close($con); //Close the database  /*delete
  $d=@mysql_connect('localhost','root','root');
  mysql_select_db('test',$d);
  mysql_query("delete from user where id=1",$d);
  mysql_close($d);
  */
  /*insert
  $i=@mysql_connect('localhost','root','root');
  mysql_select_db('test',$i);
  mysql_query("insert into user(username,password) values('ad','ad')",$i);
  mysql_close($i);
  */
  //update
  $u=@mysql_connect('localhost','root','root');
  mysql_select_db('test',$u);
  mysql_query("update user set username='aaa' where username='00'",$u);
  echo "update user set username='ax' where id=2";
  mysql_close($u);
?>