Understanding Computation Points and Computation Syntax

A good example of using computations can be illustrated by a page containing form fields for entering phone numbers. In this example, the phone number is stored in one database column; however, the data entry form breaks the phone number into three components: area code, prefix, and line number. In this example, the page items are called P10_AREA_CODE, P10_PREFIX, and P10_LINE_NUMBER.

Next, suppose you need to combine the values stored in these items into a single string. You could accomplish this by using an After Submit computation and store the combined values in an item called P10_PHONE_NUMBER.

To create a computation to store the combined values of P10_AREA_CODE, P10_PREFIX, and P10_LINE_NUMBER in new items:

1. Navigate to the appropriate Page Definition. See "Accessing the Page Definition".

2. Create a item named P10_PHONE_NUMBER to store the combined values of P10_AREA_CODE, P10_PREFIX, and P10_LINE_NUMBER. See "Differences Between Page Items and Application Items".

3. Access the Create Computation Wizard:

   • Tree view - Under the appropriate event, locate Computations. Right-click and select Create.

   • Component view - Under Computations, click the Create icon.

4. For Item Location, select Item on this Page and click Next.

5. For Computation, select P10_PHONE_NUMBER.

6. For Sequence, select the order of evaluation.

7. For Computation, you have the option of creating one of the following computation types:

   1. Static Assignment:

      • For Computation Type, select Static Assignment and click Next.

      • Enter the following computation:

        (&P10_AREA_CODE.) &P10_PREFIX.-&P10_LINE_NUMBER.
        

      • Click Next.

   2. PL/SQL Function Body:

      • For Computation Type, select PL/SQL Function Body and click Next.

      • Enter the following computation:

        DECLARE
        l_return_value  VARCHAR2(300) DEFAULT NULL;
        BEGIN
            l_return_value :=
        '('||:P10_AREA_CODE||')'||:P10_PREFIX||'-'||:P10_LINE_NUMBER;
        RETURN l_return_value;
        END;
        

      • Click Next.

   3. SQL Query (return colon separated value):

      • For Computation Type, select SQL Query (return colon separated value) and click Next.

      • Enter the following computation:

        SELECT '('||:P10_AREA_CODE||')'||:P10_PREFIX||'-'||:P10_LINE_NUMBER FROM DUAL
        

      • Click Next.

   4. PLSQL Expression:

      • For Computation Type, select PLSQL Expression and click Next.

      • Enter the following computation:

        '('||:P10_AREA_CODE||')'||:P10_PREFIX||'-'||:P10_LINE_NUMBER
        

      • Click Next.

8. Click Create.