PHP Problem

[Snodge]

I can't figure out why this isn't working. Any help is appreciated.

$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
  die("Connection failed: " . $conn->connect_error);
}

$sql = "SELECT id, username FROM usermanagement";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
  // output data of each row
  while($row = $result->fetch_assoc()) {
    echo "id: " . $row["id"]. " - Name: " . $row["username"]. " " . $row["lastname"]. "<br>";
  }
} else {
  echo "0 results";
}
$username = $row["username"];
 
$sql2 = "SELECT slot_id FROM booking_reservation where reservation_name = $username";
$result2 = $conn->query($sql2);

if ($result2->num_rows > 0) {
  // output data of each row
  while($row2 = $result2->fetch_assoc()) {
    echo "Name: " . $row2["slot_id"]. "<br>";
  }
} else {
  echo "0 results";
}

$sql1 = "SELECT * FROM booking_slots WHERE slot_id = $row2[slot_id]";
$result1 = $conn->query($sql1);

if ($result1->num_rows > 0) {
  // output data of each row
  while($row1 = $result1->fetch_assoc()) {
  echo "id: " . $row1["slot_id"]. " - Date: " . $row1["slot_date"]. " " . $row["username"]. "<br>";
  }
} else {
  echo "0 results";
}

Edited September 28, 2021 by Snodge

[requinix]

$row and $row2 both come from while loops. They're only useable within those loops.

Your code tries to show reservations for one user, and then booking slots for one reservation. Does that make sense to do? Which user and which reservation are they supposed to show?

[Barand]

Also, don't run a series of chained queries where you use the result of one query to determine the records selected in the next.

Instead use a single query with JOINs

SELECT um.id
     , um.username
     , um.lastname
     , bs.slot_id
     , bs.slot_date
FROM usermanagement um
     JOIN 
     booking_reservation br ON um.username = br.reservation_name
     JOIN 
     booking_slots bs ON br.slot_id = bs.slot_id
ORDER BY um.username, bs.slot_date