We use the update operator, , with the form
where is a relation with attribute , which is assigned the value of expression .
The expression is any arithmetic expression involving constants and attributes in relation .
Some examples:
1. To increase all balances by 5 percent.
This statement is applied to every tuple in deposit.
2. To make two different rates of interest payment, depending on balance amount:
Note: in this example the order of the two operations is important. (Why?)