Ok, now I see.
Why have you decided to store Z as Text?
As for me, the database might look like the following:
DB-Workers [Name; CostPerHour; link to DB-Works - one worker can do many DB-Works]
DB-Projects [ProjectName; link to DB-Works - one project can have many DB-Works]
DB-WorkTypes [WorkType name - to be able to select from list]
DB-Works [WorkName; DB-Project; DBWorkType; DB-Worker who does it, Number of hours, Total cost for this work].
So when the worker adds some work, the extra record in DB-Works collection will be created. When creating this record, you set:
- WorkName - text, coud be anything
- DB-Project - project should be selected
- DB-WorkType - which type of work, selected by worker
- DB-Worker - set automatically (if the worker adds the work) or manually (if manager does it)
- Number of Hours - set manually
- Total Cost - calculated based on DBWorker->CostPerHour * Number of Hours.
Then you can have the sum of all TotalCosts for the worker, if you create a list of DB-Works filtered by DB-Worker.