Right, I poster earlier with a practice table I was working on. I appreciated the reply and have been working on that.. but yesterday I got a real client's project.
I have been given the task of optimizing the database design.
The database keeps track of the transactions the company makes. A transaction is made and records are stored in several different tables.

These are the tables:
Ledger
Group
User
Opening Balance
Transaction
Transaction Type

The client would like
1) the data to be stored in ONE location and not 2 different places
2) to save disk space
3) prevent duplicate entries being

Any ideaS? I wont post the current design of the database unless necessary as I would like to try and do it all by myself but some pointers would be appreciated.
Initially I was thinking of denormalization. Eradicating the multiple tables and placing all data in one table. But this might not be the best strategy. How would you do it? What practices would you use?
ANY help would be appreciated.
Thanks!!

So....

the project calls for

the data to be stored in ONE location and not 2 different places

and

Initially I was thinking of denormalization.

.
The two DO NOT go together!

The clients does know that this is your first real project, don't they?
Because developing a financial records database is NOT something to tackle as a first project.

Do you know how to use "transactions" and "rollbacks"?