Application Programming and SQL Guide - Kmlinux

Chapter 1. Retrieving data
Result tables
You can retrieve data using the SQL statement SELECT to specify a result table.
This chapter describes how to interactively use SELECT statements to retrieve data
from DB2 tables. It includes the following sections:
v “Result tables”
v “Data types” on page 4
v “Selecting columns: SELECT” on page 5
v “Selecting rows using search conditions: WHERE” on page 8
v “Putting the rows in order: ORDER BY” on page 9
v “Summarizing group values: GROUP BY” on page 11
v “Merging lists of values: UNION” on page 13
v “Creating common table expressions: WITH” on page 14
v “Accessing DB2 data that is not in a table” on page 16
v “Using 15-digit and 31-digit precision for decimal numbers” on page 16
v “Finding information in the DB2 catalog” on page 18
For more advanced topics on using SELECT statements, see Chapter 4, “Using
subqueries,” on page 49, and Chapter 20, “Planning to access distributed data,” on
page 431.
Examples of SQL statements illustrate the concepts that this chapter discusses.
Consider developing SQL statements similar to these examples and then running
them dynamically using SPUFI or DB2 Query Management Facility (DB2 QMF).
The data retrieved through SQL is always in the form of a table, which is called a
result table. Like the tables from which you retrieve the data, a result table has rows
and columns. A program fetches this data one row at a time.
Example: SELECT statement: The following SELECT statement retrieves the last
name, first name, and phone number of employees in department D11 from the
sample employee table:
SELECT LASTNAME, FIRSTNME, PHONENO
FROM DSN8810.EMP
WHERE WORKDEPT = ’D11’
ORDER BY LASTNAME;
The result table looks similar to the following output:
LASTNAME FIRSTNME PHONENO
================ ============== ==========
ADAMSON BRUCE 4510
BROWN DAVID 4501
JOHN REBA 0672
JONES WILLIAM 0942
LUTZ JENNIFER 0672
PIANKA ELIZABETH 3782
SCOUTTEN MARILYN 1682
STERN IRVING 6432
WALKER JAMES 2986
YAMAMOTO KIYOSHI 2890
YOSHIMURA MASATOSHI 2890
© Copyright IBM Corp. 1983, 2004 3