Question

I have this sample query:

$STH = $DBH->query("SELECT id FROM table");

I want to get the first row and then loop and display all rows. So I use the following to get the first row:

$STH->setFetchMode(PDO::FETCH_ASSOC);
$first_row = $STH->fetch();
$first_row = $first_row['id'];

I use while loop to display all rows again:

while ($list = $STH->fetch()) {      
$id = $list['id'];
echo $id;
}

Now the while skips the first row and I want it to be displayed. Is there an equivalent to mysql_data_seek to reset the pointer again to the first row? I know fetchall can be used but it’s bad on memory and wasteful. I could also run the query and limit to 1 but this is not recommended as I have a query that joins multiple tables and would be very slow. Is there any other solution?

Thanks

Answer 1

I take that back looks like you can use the cursor orientation contants to select the result… sample code coming… I havent tried this so you may need to play a bit. This is also based on the assumption that a PDO::FETCH_ORI_FIRST acts like a data_seek and leaves the cursor on the first position as opposed to returning it to whatever it was before.

$stmt = $pdo->prepare('SELECT id FROM table', array(PDO::ATTR_CURSOR => PDO::CURSOR_SCROLL));
$stmt->execute();

$first = $pdo->fetch(PDO::FETCH_ASSOC, PDO::FETCH_ORI_FIRST);
$first_row = $first['id'];

// other stuff

// first iteration we rewind to the first record;
$cursor = PDO::FETCH_ORI_FIRST;

while (false !== ($row = $stmt->fetch(PDO::FETCH_ASSOC, $cursor))) {
   $id = $row['id'];
   // successive iterations we hit the "next" record
   $cursor = PDO::FETCH_ORI_NEXT; 
   echo $id;
}

---

I dont think you can rewind a statement… Assuming these blocks arent seprated by a bunch of intermediary logic id just do it in the loop.

$STH->setFetchMode(PDO::FETCH_COLUMN); // no need to pull an array
$count = 0;
while ($id = $STH->fetch()) {      
  if($count === 0) {
   $first_row = $id;
  }
  echo $id;
  $count++;
}