更新：如果条目不存在，则没有错误

Question

I'm just wondering: if an entry doesn't exist, "UPDATE" also makes an "update"? I use following code and the if-statement always has "success", especially when the email can't be found by "WHERE". Do I have to check, if the email exists in the table?

$email=...;
if ($update_stmt = $mysqli->prepare("UPDATE members SET password = ?, salt = ? WHERE email='".$email."'"))
         {
         $update_stmt->bind_param('ss', $password, $random_salt);

         $update_stmt->execute()
         header("Location: ...?success=1");
         }
         else
            header("Location: ...?error=1");

Thanks for any suggestions.

Answer 1

that's because you redirect either if the match exists or not

$update_stmt->execute()
if($update_stmt->affected_rows != 0)
{
    header("Location: ...?success=1");
}
else
{   
    header("Location: ...?error=1");
}

also remove that if before your query, so final code will look like

$update_stmt = $mysqli->prepare("UPDATE members SET password = ?, salt = ? WHERE email='".$email."'"))
$update_stmt->bind_param('ss', $password, $random_salt);
$update_stmt->execute()
if($update_stmt->affected_rows != 0)
{
    header("Location: ...?success=1");
}
else
{   
    header("Location: ...?error=1");
}

Answer 2

You need to retrieve the number of rows that were affected by the previous operation. This is provided by affected_rows .

if ($mysqli->affected_rows == 1)
{
   echo 'A record was deleted';
}

Answer 3

$email=...;
$mysqli->prepare("UPDATE members SET password = ?, salt = ? WHERE email='".$email."'"))
$update_stmt->bind_param('ss', $password, $random_salt);
$update_stmt->execute();

if ($update_stmt->affected_rows > 0){
   header("Location: ...?success=1");
         }
else
   header("Location: ...?error=1");