You'll need to add a GROUP BY
clause.
Try the following:
SELECT SUM(h.hoursworked) AS TotalHours
, p.projectname AS DocketName
, p.description AS Description
, p.archive AS Archived
, c.clientname AS Clients
FROM hours h
JOIN projects p ON h.projectid = p.projectid
JOIN clients c ON p.clientid = c.clientid
WHERE p.archive = 0
GROUP BY p.projectname, p.description, p.archive, c.clientname
ORDER BY p.projectname ASC
If you only want to see the Project Name and the Total Hours, you can do this instead:
SELECT SUM(h.hoursworked) AS TotalHours
, p.projectname AS DocketName
FROM hours h
JOIN projects p ON h.projectid = p.projectid
JOIN clients c ON p.clientid = c.clientid
WHERE p.archive = 0
GROUP BY p.projectname
ORDER BY p.projectname ASC