SQL Select - multiple children

Question

Cheers,

I have 4 tables:

 DIRECTORY - iddir, idcust, idfile
 CUSTOMERS - id_cust, fname, lname
 FILES - idf, id_dir, id_type
 TYPEF - idtype, type_name 

Basically, I want to display all values like this:

ID DIR, CUST FNAME, CUST LNAME, Name of the file

I have tried with this SQL query:

  SELECT * FROM directory
        JOIN customers ON idcust = id_cust
        JOIN files ON idfile = idf AND 
        JOIN typef ON id_type = idtype

Everything works until the last JOIN. Without it, I don't have any error, but I can't print the name of the file type which corresponds to the id of the file.

I searched, I have tried some options, but nothing worked. How can I bring to the parent table a piece of information from the "grandson table"? Thank you

PHP code

$conn = mysqli_connect("localhost", "root", "", "demodb");
if ($conn -> connect_error){
  die("Connection failed:". $conn-> connect_error);
}
$sql = "SELECT * FROM directory
    JOIN customers ON idcust = id_cust
    JOIN files ON idfile = idf AND 
    JOIN typef ON id_type = idtype";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
  while ($row = $result->fetch_assoc()) {
    echo "<tr><td>". $row["iddir"] ." </td>
    <td>". $row["fname"] ." </td>
        <td>". $row["lname"] ." </td>
        <td>". $row["id_type"] ." </td>
        <td> ". $row["type_name"] ." </td>
        </tr>";
  }
  echo " </table>";
} else {
  echo "0 result";
}
$conn->close();

Answer 1

I hope this will work for you

$conn = mysqli_connect("localhost", "root", "", "demodb");
if ($conn -> connect_error){
  die("Connection failed:". $conn-> connect_error);
}
$sql = "SELECT d.iddir, c.fname, c.lname, f.id_type, t.type_name 
    FROM directory AS d
    LEFT JOIN customers AS c ON d.idcust = c.id_cust
    LEFT JOIN files AS f ON d.idfile = f.idf 
    LEFT JOIN typef AS t ON f.id_type = d.idtype";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
  while ($row = $result->fetch_assoc()) {
    echo "<tr><td>". $row["iddir"] ." </td>
    <td>". $row["fname"] ." </td>
        <td>". $row["lname"] ." </td>
        <td>". $row["id_type"] ." </td>
        <td> ". $row["type_name"] ." </td>
        </tr>";
  }
  echo " </table>";
} else {
  echo "0 result";
}
$conn->close();