mysqli dropdown

[12Strings]

I'm attempting a mysqli dropdown to select and print one record from table and update one
field, ("lastused" ($currdate))in that record. I get the following errors: Any help?

Notice: Undefined index: lastused in C:\xampp\htdocs\home\emaildrop.php on line 109

Notice: Undefined index: target in C:\xampp\htdocs\home\emaildrop.php on line 110
target Total results: 0

Warning: mysql_fetch_array() expects parameter 1 to be resource, object given in C:\xampp\htdocs\home\emaildrop.php on line 141
target username password emailused lastused purpose saved
could not retrieve data from database

<?php
 $db = new mysqli('localhost', 'root', 'cookie', 'homedb');
if($db->connect_errno > 0)
    {die('Unable to connect to database [' . $db->connect_error . ']');}

$lastused = $_POST['lastused']; // 108 ****************************
$target = $_POST['target']; // 109 *********************************

$currdate = date('Y-m-d');    
$lastused = $currdate;
if($target=="email"){$target=$username;}
//echo "lastused $lastused";
echo "target $target";
$sql = <<<SQL
SELECT * FROM `oocust` WHERE 'target' = '$target'
SQL;
if(!$result = $db->query($sql))
    {die('There was an error running the query [' . $db->error . ']');}
while($row = $result->fetch_assoc()) 
    {echo $row['username'] . '<br />';}
echo 'Total results: ' . $result->num_rows;

$result->free(); 
$db->escape_string('This is an unescape "string"');
$db->close();
?>
<center>
  <table cellspacing=2 cellpadding=0 border=1>
   <tr> 
    <th bgcolor="#ccffff">target</TH>      
    <th bgcolor="#ccffff">username</TH> 
    <th bgcolor="#ccffff">password</TH>
    <th bgcolor="#ccffff">emailused</TH>
    <th bgcolor="#ccffff">lastused</TH>
    <th bgcolor="#ccffff">purpose</TH>
    <th bgcolor="#ccffff">saved</TH>
    <?php
while($data = mysql_fetch_array($result)) // 139 ******************************* 
    {
echo'<tr>'; 
// printing table row
echo '
<td>'.$data['target'].'</td>
<td>'.$data['username'].'</td>
<td>'.$data['password'].'</td>
<td>'.$data['emailused'].'</td>
<td>'.$data['lastused'].'</td>
<td>'.$data['purpose'].'</td>
<td>'.$data['saved'].'</td>'; 
// looping all data to be printed till last row in the table
echo'</tr>'; 
// closing table row
   }
echo '</table>';  //closing table tag
mysql_query("UPDATE emailtbl SET lastused=$lastused"); 
$result=mysql_query("select lastused from emailtbl") or die ("could not retrieve data from database");
$data=mysql_fetch_assoc($result);
echo 'Total rows updated: ' . $db->affected_rows;
echo "lastused ".$data['lastused'];
mysql_close();
   ?>
   </table></center></body></html>

[12Strings]

nobody knows mysqli?

[fastsol1]

Well first off you're mixing mysql and mysqli in the script you posted. The undefined index will result from the $_POST not having those array items when the script is run.