1. Structured Query Language (SQL)
DB Chapter 3
J.G. Zheng
June 27th 2005

2. Overview SQL Language (SQL 92)
Create Table
Select
All examples can be used with the “AmazonBook” database
This database can be downloaded from the “Course Material” section in WebCT

3. Introduction/Review What is SQL Some facts about SQL
Review: Database and DBMS (chapter 1)
SQL is a standard language accepted by relational DBMS to perform database operations
Some facts about SQL
SQL 92 is the most commonly supported version
English-like (not programming)
Case insensitive
Venders have different implementations

4. Concepts Review Relational model concepts review Relation : Table
Row : Record
Column : Field (Attribute)

5. Create Table Statement
CREATE TABLE TableName (
Column 1 Definition, Column 2 Definition, …, PRIMARY KEY (Column, [Column]) )

6. Column Definition Column Definition Format Example ColumnName DataType
BookTitle Text(200)
NumberofPages Integer
ListPrice Currency

7. Common Data Types Numeric Character/String Date
INTEGER, SMALLINT
DECIMAL(i,j), NUMBER(i,j)
Character/String
CHAR(n), VARCHAR(n)
Date
DATE, DATETIME
See textbook page for data types implemented in Access

8. Create Table Example CREATE TABLE Books ( Title VARCHAR(100),
Publisher VARCHAR(50),
ISBN CHAR(13),
Price DECIMAL(6,2),
Year INTEGER,
PRIMARY KEY (ISBN) )
Exercise: understand the statement
What is the name of this table?
How many columns are there?
Which one is the primary key?
How many characters are allowed for a book title?
What is the maximum price that can be entered for any book?

9. SELECT Statement SELECT statement retrieves data from database (query)
The result is usually another table
We will learn
Selection and projection
Sorting
Calculation
Demo all examples in Access

10. SELECT Statement Syntax
SELECT Column(s) or other expressions
FROM Table(s)
[WHERE …]
[ORDER BY ColumnName]
The order of the keyword is important

11. Simple SELECT Statement
Syntax
SELECT * (or a list of columns) FROM TableName
Wild card: *
Example
SELECT * FROM Books
SELECT BookTitle, ListPrice FROM Books

12. Use WHERE Clause Use WHERE clause to specify selection criteria
Example
SELECT * FROM Books
WHERE ListPrice = 29.99
SELECT BookTitle, ListPrice FROM Books
WHERE ListPrice < 20
Comparison Operators
“=“, “>”, “<“, “>=“, “<=“, “<>”

13. More Comparison Operators
IN (value list)
SELECT * FROM Books
WHERE ListPrice IN (19.99, 29.99, 39.99)
BETWEEN min AND max
WHERE ListPrice BETWEEN 9.99 AND 19.99

14. String Pattern Match Fuzzy query using LIKE Example
_ (underscore): single character wildcard
? in Access
% (percentage): multiple character wildcard
* in Access
Example
SELECT * FROM Books
WHERE BookTitle LIKE '*information systems*'

15. Compound Conditions
Use logical operators to connect multiple conditions
AND: an intersection of the data sets
OR: a union of the data sets
Examples
SELECT * FROM Books
WHERE ListPrice <= AND ListPrice >= 9.99
WHERE PubDate=#10/1/2003# OR PubDate=#10/1/2004#
SELECT * from Books
WHERE Publisher = 'Que' AND Binding = 'Paperback'

16. Sorting Syntax Examples ORDER BY Column(s) [ASC/DESC]
SELECT * FROM Books
ORDER BY PubDate
ORDER BY Publisher DESC, PubDate

17. Calculation Calculating columns Example
Calculated columns are not designed directly into the table
Using +, -, *, / with columns and numbers
Example
SELECT BookTitle, ListPrice, ListPrice * 0.15 AS Discount
FROM Books
WHERE ListPrice * 0.15 > 20
Usage example:
Order: unitprice*quantity

18. Built-in Functions Using these functions to do statistics Example MIN
MAX
COUNT
AVG
SUM
Example
SELECT COUNT(*) FROM Books
SELECT AVG(ListPrice) FROM Books
WHERE Publisher = 'Prentice Hall'

19. [Grouping] GROUP BY: doing math with groups SELECT COUNT(*) FROM Books
WHERE Publisher = 'Prentice Hall'; SELECT COUNT(*) FROM Books
WHERE Publisher = 'The MIT Press'; …
Or:
SELECT Publisher, COUNT(*) FROM Books
GROUP BY Publisher

20. A Complete Query SELECT ISBN, BookTitle, ListPrice, Publisher
FROM Books
WHERE
BookTitle like '*Information Systems*'
AND PubDate > #1/1/2002#
AND ListPrice < 100
ORDER BY ListPrice

21. Exercise
Using the “AmazonBook” database, use SQL or QBE to answer the following questions.
Which book is the most expensive?
How many books are under $100 of list price?
I am looking for a “database” book, no more than 50 dollars, and published after 1/1/2003; do you have any recommendations? I need the book title and its price.
What is the price per page for the books published by Que? List the book title, price, number of pages and price for page, and sort by the price per page, descending
Write out the potential results of these SQL statements

22. Updating Tables INSERT INTO UPDATE DELETE FROM Read this part yourself
To add a new record
UPDATE
To change data
DELETE FROM
To delete records
Read this part yourself

23. Summary SQL is a standard Relational DBMS language SQL statements
CREATE TABLE
SELECT
WHERE clause
DELETE FROM
INSERT INTO
UPDATE

24. Good Resources SQL Online Tutorial http://sqlcourse.com/