Linking??

[ec]

you know the way in access, you can link tables to ensure that a value cannot be entered in table 2 unless it exists in table one?

how would you do that with php and mysql?

[trq]

Check if the value exists in table1 before inserting it into table2.

[ec]

I think i've got it working now using this

 

//Making sure that pupil number exists

//Check for duplicate pupil no

$qry = "SELECT count(*) AS c FROM pupil WHERE pupilno='$pupilno'";

$result = mysql_query($qry);

if($result) {

$result_array = mysql_fetch_assoc($result);

if($result_array['c'] < 1) {

$errmsg_arr[] = 'Pupil number is not in use';

$errflag = true;

}

@mysql_free_result($result);

}

else {

die("Query failed");

}

 

 

is there any eaiser way of doing it?

[trq]

<?php

  $qry = "SELECT pupilno FROM pupil WHERE pupilno='$pupilno'";
  if ($result = mysql_query($qry)) {
    if (mysql_num_rows($result)) {
      $result_array = mysql_fetch_assoc($result);
    } else {
      $errmsg_arr[] = 'Pupil number is not in use';
      $errflag = true;
    }
  } else {
    die("Query failed");
  }

?>

[aschk]

You can use foreign key constraints, i.e. you need to insert a valid foreign key into table 2 for it to be a valid entry. Otherwise it fails.