How to add some column with | delimiter

PHP

Hi experts,

I have this program where i called the data from database.
The datafield i need to look for is absent and only absent will print out on the screen
In this database i need to retrieved data that with condition 1 to 7 (as day)
I have 3 value that i put it in an array e.g: $student = array(18,22,34) where i retrieved from database
I should have output of |||||||| if the student is not absent from day 1 to 7
But my problem now is say : studentID 18 only absent once on tuesday is will only print the string as below

absent|
and not
|absent||||||

below is my code

I need to find When a student is absent and the fieldname is ABSENT
I have 3 value that i put it in an array e.g: $student = array(18,22,34) where i retrieved from database
i called this array as ID's
since one week have 7 days so i create an array as array(1,2,3,4,5,6,7)

i do as follow

function ABSENT()
{
$DAY= array(1,2,3,4,5,6,7);

  foreach($this->Getstudent as $student)
   {
      for ($j=0; $j<sizeof($IndexOrder);$j++)
     {
        $query = "SELECT ABSENT
                   FROM $ABSENTTABLE
                  WHERE STUDENT = \"$student\" AND INDEXORDER = $DAY[$j]";
 
        $result = mysql_query($query);
       
         while($row = mysql_fetch_array($result))
           {
          $this->GetABSENT  .=  ''.$row['ABSENT'].'|';  
           }
     }
  }
  mysql_close($dbLink);
}
 
THE CURRENT RESULT I GET IS EXAMPLE 22 ABSENT 2 DAYS ON MONDAY AND FRIDAY IT ONLYT PRINT OUT
ABSENT|ABSENT|
AND NOT
ABSENT||||ABSENT|||

how to solve this