1. The questing beast Sir Thomas Mallory
SQL
The questing beast
Sir Thomas Mallory

2. SQL A standard for relational database SQL skills are in demand
American National Standards Institute (ANSI)
International Organization for Standardization (ISO)
SQL skills are in demand
Developed by IBM
Object-oriented extensions created

3. SQL A complete database language Data definition Data manipulation
Definition of tables and views
CREATE
Data manipulation
Specifying queries
Maintaining a database
SELECT, INSERT, UPDATE, and DELETE
Data control
Controlling a database
GRANT and REVOKE

4. CREATE
CREATE DATABASE whatever COLLATE latin1_general_cs; USE whatever; CREATE TABLE share ( shrcode CHAR(3), shrfirm VARCHAR(20)NOT NULL, shrprice DECIMAL(6,2), shrqty DECIMAL(8), shrdiv DECIMAL(5,2), shrpe DECIMAL(2), PRIMARY KEY(shrcode));

5. Data manipulation statements
INSERT
UPDATE
DELETE
SELECT

6. INSERT
INSERT INTO share (shrcode,shrfirm,shrprice,shrqty,shrdiv, shrpe) VALUES ('FC','Freedonia Copper',27.5,10529,1.84,16); Or

7. UPDATE and DELETE UPDATE share SET shrprice = 31.50
WHERE shrcode = 'FC’
DELETE FROM share
WHERE shrfirm = 'Freedonia Copper’;
NOTE: DELETE only eliminates one or multiple rows. If you want to delete ALL rows (i.e., delete an entire table) you need to use DROP (i.e., DROP TABLE share)

8. SELECT General format SELECT * FROM share WHERE shrpe >= 12
SELECT[DISTINCT] [SUM, AVG, MIN, or MAX] column(s)
FROM table(s)
[WHERE condition]
[GROUP BY column(s)]
[HAVING condition]
[ORDER BY column(s)];
SELECT * FROM share WHERE shrpe >= 12
ORDER BY shrpe DESC, shrfirm;

9. Data types

10. Check the manual for full details
Data types
BOOLEAN
True, False, or Unknown
INTEGER
31 binary digits
good for ± 2 billion
SMALLINT
15 binary digits
good for ± 32000
DECIMAL(p,q)
Commercial applications. If p=3 and q=2,what is the maximum possible value in dollars?
FLOAT
Scientific work
Check the manual for full details

11. Check the manual for full details
Data types
CHAR and VARCHAR
Character strings (i.e., non-numeric)
What is the difference between CHAR and VARCHAR?
DATE, TIME, TIMESTAMP, and INTERVAL
Date (yyyymmdd ( for November 4, 2012)
Time (hhmmss) (20:30:01 for 8:30pm and 1s)
Interval (single value expressed in some unit or units of time (e.g., 6 years)
BLOB and CLOB
Binary large object (e.g., graph, audio, image)
Character large object (e.g., reports, contracts)
Check the manual for full details

12. Formatting Number Date
FORMAT(x,d) formats the number x with d decimal places with commas
SELECT FORMAT(amount,2) FROM Payments;
Date
DATE_FORMAT (date, format) provides a flexible way of reporting dates
SELECT DATE_FORMAT(orderDate, '%W, %M %Y') from Orders;
SELECT DATE_FORMAT(orderDate, '%Y-%m-%d') from Orders;
SELECT DATE_FORMAT(orderDate, '%D, %M %Y') from Orders;

13. Exercise
Using the ClassicModels database, report customer name and the total payment amount for each customer to the nearest dollar and list in descending value

14. Collation sequence
Defines how to sort individual characters in a particular language
English
A B C … X Y Z
Norwegian
A B C … X Y Z Æ Ø Å

15. Collation sequence
Can specify a collation sequence at the database, table, and, column level
Good practice to specify at the database level
CREATE DATABASE ClassicModels
COLLATE latin1_general_cs;
cs indicates case sensitivity

16. Creating a View
A view does not physically exist as stored data; it is an imaginary (virtual) table constructed from existing tables as required
General format
CREATE VIEW view (column(s))
AS subquery;

17. When Do We Create Views? Restrict access to a table
Create a view to restrict access to the table share.
CREATE VIEW stklist AS SELECT stkfirm, stkprice FROM stock;
Handle derived data
Create a view with stock’s yield computed.
CREATE VIEW stk AS SELECT stkfirm, stkprice, stkqty, stkdiv/stkprice*100 FROM stock;

18. When Do We Create Views? Avoid writing common SQL queries
Create a view to perform the frequent join between stock and nation and to convert all share prices from the local currency to British pounds.
CREATE VIEW stkvalue AS SELECT natname, stkfirm, stkprice*exchrate, stkqty, stktprice*exchrate*stkqty FROM stock, nation WHERE stock.natcode = nation.natcode;

19. Dropping a View
Used to delete a view from the system. A view may be dropped because it needs to be redefined or is no longer used
General format
DROP VIEW view;

20. Product
All rows of the first table concatenated with all possible rows of the second table
Form the product of stock and nation
SELECT * FROM stock, nation;

21. Product – CREATE A VIEW
Find the percentage of Australian stocks in the portfolio.
CREATE VIEW austotal AS
SELECT COUNT(*) AS ’A' FROM nation, stock
WHERE natname = 'Australia'
AND nation.natcode = stock.natcode;
CREATE VIEW total AS
SELECT COUNT(*) AS ’B' FROM stock;
SELECT A/B*100
AS percentage FROM austotal, total;
18.75

22. PRODUCT (alternative)
Find the percentage of Australian stocks in the portfolio.
SELECT FORMAT((SELECT COUNT(*) FROM nation, stock WHERE nation.natcode = stock.natcode
AND natname = 'Australia')*100/(SELECT COUNT(*) FROM stock),2) AS Percentage;
SELECT (SELECT COUNT(*) FROM nation, stock WHERE nation.natcode = stock.natcode
AND natname = 'Australia')*100/(SELECT COUNT(*) FROM stock) AS Percentage;
18.75

23. Join
Join creates a new table from two existing tables by matching on a column common to both tables
Equijoin
The new table contains two identical columns
SELECT * FROM stock, nation
WHERE stock.natcode = nation.natcode;

24. Correlated subquery
The inner query is evaluated many times rather than once
Find those stocks where the quantity is greater than the average for that country.
SELECT natname, stkfirm, stkqty FROM stock, nation
WHERE stock.natcode = nation.natcode
AND stkqty >
(SELECT AVG(stkqty) FROM stock
WHERE stock.natcode = nation.natcode);

25. Correlated subquery SELECT natname, stkfirm, stkqty FROM stock, nation
WHERE stock.natcode = nation.natcode
AND stkqty >
(SELECT AVG(stkqty) FROM stock
WHERE stock.natcode = nation.natcode);
nation
natcode
natname
exchrate UK
United Kingdom
1.00
USA
United States
0.67
AUS
Australia
0.46
IND
India
0.0228
stock
stkcode
stkfirm
stkprice
stkqty
stkdiv
stkpe
natcode FC
Freedonia Copper
27.50
10529
1.84 16 UK PT
Patagonian Tea
55.25
12635
2.50 10 AR
Abyssinian Ruby
31.82
22010
1.32 13
SLG
Sri Lankan Gold
50.37
32868
2.68
ILZ
Indian Lead &Zinc
37.75
6390
3.00 12 BE
Burmese Elephant
.07
154713
0.01 3 BS
Bolivian Sheep
12.75
231678
1.78 11 NG
Nigerian Geese
35.00
12323
1.68 CS
Canadian Sugar
52.78
4716 15
ROF
Royal Ostrich Farms
33.75  6 MG
Minnesota Gold
53.87
816122
1.00 25
USA GP
Georgia Peach
2.35
387333
.20 5 NE
Narembeen Emu
12.34
45619 8
AUS QD
Queensland Diamond
6.73
89251
.50 7 IR
Indooroopilly Ruby
15.92
56147 20 BD
Bombay Duck
25.55
167382
IND

26. Correlated subquery

27. Correlated subquery Clue
The need to compare each row of a table against a function (e.g., average or count) for some rows of a column
Find those stocks where the quantity is greater than the average for that country

28. Aggregate functions
COUNT
SUM
AVG
MAX
MIN

29. Security Data is a valuable resource Access should be controlled
SQL security procedures
CREATE VIEW
Authorization commands

30. GRANT Defines a user’s privileges
The keyword privilege can be ALL PRIVILEGES or chosen from
SELECT
UPDATE
DELETE
INSERT
Privileges can be granted to everybody using the keyword PUBLIC or to selected users by specifying their user identifier

31. GRANT General format WITH GRANT OPTION
GRANT [ALL PRIVILEGES, SELECT, UPDATE, DELETE, INSERT]
ON [table(s), view(s)]
TO [user(s), PUBLIC]
[WITH GRANT OPTION];
WITH GRANT OPTION
Permits a user to pass privileges to another user

32. Using GRANT Give Alice all rights to the STOCK table.
GRANT ALL PRIVILEGES ON stock TO alice;
Permit the accounting staff, Todd and Nancy, to update the price of a stock.
GRANT UPDATE (stkprice) ON stock TO todd, nancy;
Give all staff the privilege to select rows from ITEM.
GRANT SELECT ON item TO PUBLIC;
Give Alice all rights to view STK.
GRANT SELECT, UPDATE, DELETE, INSERT ON stk
TO alice;
Why wasn’t ALL PRIVILEGES used?
Since STK is a view, ALICE cannot be granted ALL PRIVILEGES since this would include ALTER and INDEX privileges for a view

33. REVOKE Removes privileges General Format Cascading REVOKE
REVOKE privileges ON object FROM users;
Cascading REVOKE
Reverses use of the WITH GRANT OPTION
When a user’s privileges are revoked, all users whose privileges were established using WITH GRANT OPTION are also revoked

34. Using REVOKE General Format REVOKE privileges ON object FROM users;
Remove Sophie's ability to select from ITEM.
REVOKE SELECT ON item FROM sophie;
Nancy is no longer permitted to update stock prices.
REVOKE UPDATE ON stock FROM nancy;
A revoked UPDATE is not column specific

35. Key points—SQL Not a complete programming language
Data definition, manipulation, and control
Several data types (STRING, NUMERIC)
Formatting capability (FORMAT (__,__))
Correlated subquery