This document discusses SQL commands for creating and altering database tables. It covers creating tables with various data types and column constraints like primary keys, unique constraints, foreign keys, and default values. It also covers altering table structures by adding, modifying, or dropping columns and dropping entire tables.

1. SQL
Creating and Altering Tables

2. This is DDL
DDL - Data Definition Language
● Creating and Altering the structure of the
database.
● You are building the data dictionary!

3. CREATE TABLE
CREATE TABLE ARTISTS
(ARTIST_ID INT,
ARTIST_NAME
VARCHAR(60),
ARTIST_DOB DATE,
POSTER_IN_STOCK BOOLEAN);

4. Don’t Forget Data Types!
CHAR DATE
TIMESTAMP
VARCHAR TIME BOOLEAN
NUMERIC REAL
DECIMAL DOUBLE
INT PRECISION
SMALLINT FLOAT

5. User Defined (Data) Types
CREATE TYPE SALARY AS NUMERIC(8,2)
FINAL;
CREATE TABLE EMPLOYEES
(EMPLOYEE_ID
INTEGER,
EMPLOYEE_SALARY SALARY);

6. Default Values
CREATE TABLE ARTISTS
(ARTIST_ID INT,
ARTIST_NAME VARCHAR(60),
PLACE_OF_BIRTH VARCHAR(60)
DEFAULT ‘Unknown’);

7. ALTER TABLE
ALTER TABLE ARTISTS
ADD COLUMN ARTIST_DOB DATE;

8. ALTER COLUMN
ALTER TABLE ARTISTS
ALTER COLUMN PLACE_OF_BIRTH SET
DEFAULT ‘Unknown’;
ALTER TABLE ARTISTS
ALTER COLUMN PLACE_OF_BIRTH DROP
DEFAULT;

9. DROP COLUMN
ALTER TABLE ARTISTS
DROP COLUMN PLACE_OF_BIRTH
CASCADE;

10. DROP TABLE
DROP TABLE ARTISTS CASCADE;
Not the Same as:
TRUNCATE TABLE ARTISTS;
Or
DELETE * FROM ARTISTS;

11. Required or Optional?
CREATE TABLE CD_ARTISTS
(ARTIST_ID INT NOT NULL,
ARTIST_NAME VARCHAR(60) NOT NULL,
PLACE_OF_BIRTH VARCHAR(60));

12. Unique Constraints
CREATE TABLE CD_INVENTORY
(ARTIST_NAME VARCHAR(40),
CD_NAME VARCHAR(60),
COPYRIGHT INT,
CONSTRAINT UN_ARTIST_CD UNIQUE
(ARTIST_NAME, CD_NAME));

13. Primary Keys
CREATE TABLE CD_ARTISTS
(ARTIST_ID INT,
ARTIST_NAME VARCHAR(60),
AGENCY_ID INT,
CONSTRAINT PK_ARTIST_ID PRIMARY_KEY
(ARTIST_ID, ARTIST_NAME);

14. Foreign Keys
CREATE TABLE CD_TITLES
(CD_TITLE_ID INT,
CD_TITLE VARCHAR(60),
PUBLISHER_ID INT,
FK_PUBLISHER_ID FOREIGN KEY
(PUBLISHER_ID) REFERENCES CD_PUBLISHERS
(PUBLISHER_ID));

15. Column Constraints
CREATE TABLE CD_TITLES
(CD_TITLE INT,
CD_TITLE VARCHAR(60) NOT NULL,
IN_STOCK INT
NOT NULL,
CONSTRAINT CK_IN_STOCK
(IN_STOCK > 0 AND IN_STOCK < 30));