The Relational Model: Manipulation

• Operators to allow modification of data
• In relational theory, insert, update and delete can all be thought of as assignment
• Every modification to the data in a relation variable changes the value of that variable.

# Insert
Part = { (all current tuples of Part),
         [ part_number: 5,
           part_name: "Big Bird's Head",
           color: "yellow" ],
       };

# Update
Part = { (all current tuples except part_number == 5),
         [ part_number: 5,
           part_name: "Big Bird's Bloody Head",
           color: "red" ],
       };

# Delete
Part = { (all current tuples except part_number == 5) };