Pathmaker Programming Guide

Using Null Values
Defining Data for a NonStop SQL Pathmaker Application
C–6 067868 Tandem Computers Incorporated
Example 1: Operation : READ FIRST
Cursor on : SPOUSENAME
Repetition count : 4
In this READ FIRST, all the rows of the table are returned, ordered by
SPOUSENAME. Notice that the row with the null SPOUSENAME does not
appear:
MEMBERNUM MEMBERNAME SPOUSENAME
--------------------------------------------
| 3 | Jim | Michelle |
--------------------------------------------
| 1 | John | Paula |
--------------------------------------------
| 4 | Janis | Robert |
--------------------------------------------
Example 2: Operation : READ FIRST
Cursor on : MEMBERNAME
Repetition count : 4
In the second example, assume you placed the cursor on MEMBERNAME. In this
case, rows with null values in the SPOUSENAME column will be returned if they
otherwise satisfy the request:
MEMBERNUM MEMBERNAME SPOUSENAME
--------------------------------------------
| 4 | Janis | Robert |
--------------------------------------------
| 3 | Jim | Michelle |
--------------------------------------------
| 1 | John | Paula |
--------------------------------------------
| 2 | Mary | ???????? |
--------------------------------------------
In this example, you would retrieve the same rows (although the ordering would
be different) if you placed the cursor on MEMBERNUM instead of
MEMBERNAME.
All other read operations (READ EXACT, READ APPROXIMATE, READ
GENERIC) work the same way.