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Counting a row in sql

Posted on 2009-03-30
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Last Modified: 2012-05-06
Hey,

I have to display a column that is a count of another row on another table. I have done it using two queries but I would like to find out how to do it in one query.

The column to display will be "Number of Exercises" and it will count the number of "Exercise Id's" on the Session Details table.

I have attached my code and the tables to help you all understand how they are related.

Thanks.
$sql = "Select Sessions.Date_Created, Sessions.Created_By
        From Sessions, Session_Details
        Where Sessions.Member_Id = '$clientID'";
    $result = mysql_query($sql);
    while ($ROW = mysql_fetch_array($result)) {
        $sessionID = $ROW['Session_Id'];
		$sessionDate = $ROW['Date_Created'];
        echo date('F d, Y',strtotime($sessionDate));
        echo $createdBy = $ROW['Created_By'];
	}
//    Retrieve the number of exercises in that session
    $sql2 = "Select Session_Details.Exercise_Id
        From Session_Details, Sessions
        Where Sessions.Member_Id = '$clientID' AND Session_Details.Session_Id = Sessions.Session_Id";
    $result2 = mysql_query($sql2);
    echo mysql_num_rows($result2);

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tables.bmp
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Question by:tqrecords
  • 2
3 Comments
 
LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 24023920
you mean:
Select s.Date_Created, s.Created_By, count(sd.exercice_id) exercice_count
From Sessions s 
left join Session_Details sd
  on sd.session_id = s.session_id
Where s.Member_Id = '$clientID'
group by s.Member_id

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Author Comment

by:tqrecords
ID: 24024294
Thanks, but there is also one more join I need to make from another table.

There is a created_by column in the Sessions table and it is an integer value.

The created_by will match the member_id on the members table and will return the name of the member.

I have the updated tables attached.


tables.bmp
0
 
LVL 143

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 500 total points
ID: 24026796
simply add a join
Select s.Date_Created, s.Created_By, count(sd.exercice_id) exercice_count
 , m.username created_by_user
From Sessions s 
left join Session_Details sd
  on sd.session_id = s.session_id
join members m
  on m.member_id = s.created_by
Where s.Member_Id = '$clientID'
group by s.Member_id

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