Relational Algebra Operations Continued

Modification of the Database

 Deletion

Here are several examples of relational algebra delete operations:

         Delete all of Smith’s account records

         Delete all loans with amount in the range 0 to 50.

    Delete all accounts at branches located in Dhaka.  

 

Insertion

Suppose we wish to insert the fact that Smith has Tk1200 in account A-973 at Kakrail branch. We write:

Updating

Suppose that interest rates are being made, and that all branches are to be increased by 5%.  For this we require an update operation.

 

Suppose that accounts with balances over Tk10,000 receive 6% interest, where as all others receive 5%.