PHP上的空字段处理

Question

I have a table named hr events where, in one field, it outputs when a certain employee went on maternity leave;

On the return_date field, it displays the date when the employee got back from the maternity leave.

If the employee has not come back yet, we set a default value, as seen on CREATE statement below: CREATE (return_date DATE NOT NULL DEFAULT '0000-00-00',);

There is one last field on this report where it is supposed to show the employee's final return date to her activities: (c.return_date ,'%d/%m/%Y') AS c_return_date. As an SQL beginner, i'm struggling with this: whenever we have a (default 0000-00-00) value, c.return_date brings some sort of aleatory date, like: e.g 12/01/1999 , tho' it's a NULL field.

I've been trying to treat this with ISNULL(c.return_date, '') or ISNULL(c.return_date, 0) but it just doesn't work. In the above scenario, this last field should be blank or anything but this '12/01/1999'.

As for PHP, and that's why I'm editing this topic, I think there could be a way out of this by addressing this issue inside the php script:

<?php
    $retorno = (!empty($row['c_return_date'])) ? $row['c_return_date'] : $row['a_return_date'];
    $data = explode('-', $retorno);
    echo date("d/m/Y", mktime(0, 0, 0, $data[1], $data[2] + 1, $data[0]));
?>

I'm currently trying to figure out (actually, more figuring out how does this script works) how to validate this script to, in case of a return date like 0000-00-00 (which means the employee has not come back yet to her activities), not display these sort of output like 12/01/1999.

Answer 1

After all, it was a php script issue.

<?php
                         $retorno = (!empty($row['c_return_date'])) ? $row['c_return_date'] : $row['a_return_date'];
                         $data = explode('-', $retorn);
                         echo date("d/m/Y", mktime(0, 0, 0, $date[1], $date[2] + 1, $date[0]));
                         ?>

I just needed to put a contitional statement on the script above, to prevent c_return_datefrom displaying anything in case a_return_date is 0000-00-00. Take a look at the if / else clauses:

<?php
                          if ($row['a_return_date'] != "0000-00-00"){
                            $return = (!empty($row['c_return_date'])) ? $row['c_return_date'] : $row['a_return_date'];
                            $data = explode('-', $return);
                             echo date("d/m/Y", mktime(0, 0, 0, $date[1], $date[2] + 1, $date[0]));
                             } else $row['a_return_date_br'] = "-";
                             ?>

Thank you all. Hope it helps somebody else.