Application Programming and SQL Guide - Kmlinux

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Contents
About this book . . . . . . . . . . . . . . . . . . . . . . . . xix
Who should read this book . . . . . . . . . . . . . . . . . . . . xix
Terminology and citations . . . . . . . . . . . . . . . . . . . . . xix
How to read the syntax diagrams . . . . . . . . . . . . . . . . . . xx
Accessibility . . . . . . . . . . . . . . . . . . . . . . . . . . xxi
How to send your comments . . . . . . . . . . . . . . . . . . . . xxi
Summary of changes to this book . . . . . . . . . . . . . . . . xxiii
Part 1. Using SQL queries . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter 1. Retrieving data . . . . . . . . . . . . . . . . . . . . 3
Result tables . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Data types . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Selecting columns: SELECT . . . . . . . . . . . . . . . . . . . . 5
Selecting all columns: SELECT * . . . . . . . . . . . . . . . . . . 5
Selecting some columns: SELECT column-name . . . . . . . . . . . . 6
Selecting derived columns: SELECT expression . . . . . . . . . . . . 7
Eliminating duplicate rows: DISTINCT . . . . . . . . . . . . . . . . 7
Naming result columns: AS . . . . . . . . . . . . . . . . . . . . 7
Selecting rows using search conditions: WHERE . . . . . . . . . . . . . 8
Putting the rows in order: ORDER BY . . . . . . . . . . . . . . . . . 9
Specifying the sort key . . . . . . . . . . . . . . . . . . . . . 10
Referencing derived columns . . . . . . . . . . . . . . . . . . . 10
Summarizing group values: GROUP BY . . . . . . . . . . . . . . . . 11
Subjecting groups to conditions: HAVING . . . . . . . . . . . . . . . 12
Merging lists of values: UNION . . . . . . . . . . . . . . . . . . . 13
Using UNION to eliminate duplicates . . . . . . . . . . . . . . . . 13
Using UNION ALL to keep duplicates . . . . . . . . . . . . . . . . 13
Creating common table expressions: WITH . . . . . . . . . . . . . . 14
Using WITH instead of CREATE VIEW . . . . . . . . . . . . . . . 14
Using common table expressions with CREATE VIEW . . . . . . . . . 15
Using common table expressions when you use INSERT . . . . . . . . 15
Using recursive SQL . . . . . . . . . . . . . . . . . . . . . . 15
Accessing DB2 data that is not in a table . . . . . . . . . . . . . . . 16
Using 15-digit and 31-digit precision for decimal numbers . . . . . . . . . 16
Finding information in the DB2 catalog . . . . . . . . . . . . . . . . 18
Displaying a list of tables you can use . . . . . . . . . . . . . . . 18
Displaying a list of columns in a table . . . . . . . . . . . . . . . 18
Chapter 2. Working with tables and modifying data . . . . . . . . . . 19
Working with tables . . . . . . . . . . . . . . . . . . . . . . . 19
Creating your own tables: CREATE TABLE . . . . . . . . . . . . . 19
Working with temporary tables . . . . . . . . . . . . . . . . . . 21
Dropping tables: DROP TABLE . . . . . . . . . . . . . . . . . . 25
Working with views . . . . . . . . . . . . . . . . . . . . . . . 25
Defining a view: CREATE VIEW . . . . . . . . . . . . . . . . . 25
Changing data through a view . . . . . . . . . . . . . . . . . . 26
Dropping views: DROP VIEW . . . . . . . . . . . . . . . . . . 27
Modifying DB2 data . . . . . . . . . . . . . . . . . . . . . . . 27
Inserting rows: INSERT . . . . . . . . . . . . . . . . . . . . . 27
Selecting values as you insert: SELECT from INSERT . . . . . . . . . 31
Updating current values: UPDATE . . . . . . . . . . . . . . . . . 36
© Copyright IBM Corp. 1983, 2004 iii