Application Programming and SQL Guide - Kmlinux

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For information about using the INSERT statement, see “Inserting rows: INSERT”
on page 27.
Creating a new employee table
You can use the following statements to create a new employee table called YEMP.
CREATE TABLE YEMP
(EMPNO CHAR(6) PRIMARY KEY NOT NULL,
FIRSTNME VARCHAR(12) NOT NULL,
MIDINIT CHAR(1) NOT NULL,
LASTNAME VARCHAR(15) NOT NULL,
WORKDEPT CHAR(3) REFERENCES YDEPT
ON DELETE SET NULL,
PHONENO CHAR(4) UNIQUE NOT NULL,
HIREDATE DATE ,
JOB CHAR(8) ,
EDLEVEL SMALLINT ,
SEX CHAR(1) ,
BIRTHDATE DATE ,
SALARY DECIMAL(9, 2) ,
BONUS DECIMAL(9, 2) ,
COMM DECIMAL(9, 2) );
This statement also creates a referential constraint between the foreign key in
YEMP (WORKDEPT) and the primary key in YDEPT (DEPTNO). It also restricts all
phone numbers to unique numbers.
If you want to change a table definition after you create it, use the statement ALTER
TABLE. If you want to change a table name after you create it, use the statement
RENAME TABLE.
You can change a table definition by using the ALTER TABLE statement only in
certain ways. For example, you can add and drop constraints on columns in a table.
You can also change the data type of a column within character data types, within
numeric data types, and within graphic data types. You can add a column to a
table. However, you cannot drop a column from a table.
For more information about changing a table definition by using ALTER TABLE, see
Part 2 (Volume 1) of DB2 Administration Guide. For other details about the ALTER
TABLE and RENAME TABLE statements, see Chapter 5 of DB2 SQL Reference.
Working with temporary tables
When you need a table only for the duration of an application process, you can
create a temporary table. There are two kinds of temporary tables:
v Created temporary tables, which you define using a CREATE GLOBAL
TEMPORARY TABLE statement
v Declared temporary tables, which you define using a DECLARE GLOBAL
TEMPORARY TABLE statement
SQL statements that use temporary tables can run faster because of the following
reasons:
v DB2 does no logging (for created temporary tables) or limited logging (for
declared temporary tables).
v DB2 does no locking (for created temporary tables) or limited locking (for
declared temporary tables).
Temporary tables are especially useful when you need to sort or query intermediate
result tables that contain a large number of rows, but you want to store only a small
subset of those rows permanently.
Chapter 2. Working with tables and modifying data 21