1. CS 3630 Database Design and Implementation

2. Due Wednesday, April 4, by 5 PM Class dropbox on K: drive
Project Phase II
Due Wednesday, April 4, by 5 PM
Class dropbox on K: drive

3. Assignment 8
Due Friday, April 6, by 5 PM

4. Aggregate Functions: Produce a single value from a set
Count
Max
Min
Sum
Avg …

5. SQL Aggregate Functions
-- Max, Min, Avg, Sum
Select Max(price), Min(price), Avg(price)
From room;

6. Formatting -- Formatting
Col MaxPrice format $99.00 heading "Max Price"
Select Max(price) MaxPrice,
Min(price) MinPrice,
Avg(price) AvgPrice
From room;

7. Formatting -- Formatting
Col MaxPrice format $ heading "Max Price"
Col MinPrice format $ heading "Min Price"
Col AvgPrice format $ heading "Avg Price"
Select Max(price) MaxPrice,
Min(price) MinPrice,
Avg(price) AvgPrice
From room;

8. SQL Aggregate Functions
-- Room_No char(4)
Select Max(room_no), Min(room_no)
From room;

9. SQL Aggregate Functions
// Room_No char(4)
// No average or sum on strings!
Select Avg(room_no), Sum(room_no)
From room;

10. Max/Min Dates
Col Min(Date_From) Format a20 Heading 'Earlist Date_From'
Col Max(Date_To) Format a20 Heading 'Latest Date_To'
Select Min(Date_From), Max(Date_To)
From Booking;

11. Max/Min Dates col "Earliest Date from" format a20
col "Latest Date To" format a20
Select To_Char(Min(Date_From), 'Mon dd yyyy')
"Earliest Date from",
To_Char(Max(Date_To), 'Mon dd yyyy')
"Latest Date To"
From Booking;

12. Incorrect! col "Earliest Date from" format a20
col "Latest Date To" format a20
Select Min(To_Char(Date_From, 'Mon dd yyyy'))
"Earliest Date from",
Max(To_Char(Date_To, 'Mon dd yyyy'))
"Latest Date To"
From Booking;

13. Count -- Count(*): number of all records
-- count(hotel_no): number of Hotel_No
-- Count(unique Hotel_No):
number of distinct Hotel_No
Select count(*), count(hotel_no),
count(unique hotel_no)
From room;
Pause
Select *
From room
Order by hotel_no;

14. Count -- Does not count null values select count(*), count(address)
From guest;
Select *
From guest;

15. Aggregate Functions with Distinct/Unique
Select Avg(Price)
From room;
-- With Distinct
Select Avg(Distinct Price)
Select Avg(Unique Price)
Select *
From room
Order by price;

16. Aggregate Functions with Where
-- With where clause
-- Avg is applied after Where clause
col "Average Price" format $999.00
Select Avg(Price) "Average Price"
From room
Where rtype = 'Family';
Select Avg(Price) "Average Price"
Where rtype = 'Single';
Where rtype = 'Double';

17. Aggregate Functions with Where
-- With where clause
-- Avg is applied after Where clause
Select 'Average Price of Family rooms: ',
Avg(Price)
From room
Where rtype = 'Family';
Pause
Prompt Run time error!
Select rtype, Avg(Price)

18. One record for each group.
Group By Clause
Count, Avg
Select
Group By
Count, Avg
Count, Avg
One record for each group.

19. Group By Select Avg(Price) From room Group by rtype;
Select rtype, Avg(Price)

20. Group By Clause
For each hotel, display Hotel_No with the number of rooms.
Select Hotel_No, Count(*)
From Room
Group By Hotel_No;
Hotel_No
Room_No
Price
H01
R001 30
R002 35
H05
R003 40
R103 45
R101 50
Hotel_No
Room_No
Price
H01
R001 30
R002 35
R103 45
H05
R003 40
R101 50
Hotel_No
Count
H01 3
H05 2

21. What can be selected with Group By Clause
Can select Hotel_No, the group by field
Can select aggregate functions on any other fields such as Max(Room_No) or Avg(Price)
Hotel_No
Room_No
Price
H01
R001 30
R002 35
R103 45
H05
R003 40
R101 50
Hotel_No
Room_No
Price
H01
R001 30
R002 35
R103 45
H05
R003 40
R101 50
Hotel_No
Max(Room_No)
Avg(Price)
H01
R103
36.67
H05
R101 45

22. What CANNOT be selected with Group By Clause
Cannot select other fields (without aggregate function) not in the group by clause
ORA-00979: not a GROUP BY expression
Hotel_No
Room_No
Price
H01
R001 30
R002 35
R103 45
H05
R003 40
R101 50
Hotel_No
Room_No
Price
H01
R001 30
R002 35
R103 45
H05
R003 40
R101 50
Hotel_No
Room_No
Price
H01 ?
H05

23. Group By Clause ? Select Group By ? ? One record for each group!
What can be selected?
Aggregate functions
Group by fields

24. One Record for Each Group
Select Hotel_no, Count(*), Max(Price)
From Room
Group by Hotel_No;
Select Hotel_no, Room_No, rtype,
Price
-- not a Group By expression

25. Group by More Than One Field
Select Hotel_No, rtype, Max(Price)
From Room
Group By Hotel_no, rtype
Order By Hotel_no, rtype

26. Order After Group by Select Hotel_no, Count(*), Max(Price) From Room
Group by Hotel_No
Order by Count(*);

27. Group By Clause ? Select Group By ? ?
What if we don’t want all groups?
Having on groups

28. Having to select groups
Select Hotel_no, Count(*), Max(Price)
From Room
Group by Hotel_No;
Pause
Group by Hotel_No
Having Count(*) >= 5;

29. Group By Where before Group by to select records
Having after Group by to select groups
Select Hotel_no, Count(*), Max(Price)
From Room
Where rtype = 'Single'
Group by Hotel_No
Having Max(Price) < 100;

30. Where before Group by to select records Having after Group by
From Room
Order by rtype;
pause
Where rtype = 'Single';
Select Hotel_no, Count(*), Max(Price)
Where rtype = 'Single'
Group by Hotel_No;
Pause
Group by Hotel_No
Having Max(Price) < 100;
Where before Group by
to select records
Having after Group by
to select groups
Let’s do it in 4 steps:
From
Where
Group By
Having

31. Where before Group by Having after Group by Order by last
Select Hotel_no, Count(*), Max(Price)
From Room
Where rtype in ('Double', 'Single')
Group by Hotel_No
Order by Count(*);
pause
Having Count(*) > 3
Order by Count(*) desc;

32. Group By Clause Execution Order Where (condition on records) Group by
Having (condition on groups)
Order by
(Select)

33. Script File Style Prompt Prompt 9.
Prompt For each hotel that has more than
Prompt one Single room, list hotel number
Prompt with number of Single rooms the hotel
Prompt has and the highest price of
Prompt such rooms of the hotel.
Col Count(*) Format 99 heading "Single Rooms"
Col Max(Price) format $ heading "Max Price"
Select Hotel_no, Count(*), Max(Price)
From Room
Where rtype = 'Single'
Group by Hotel_No
Having Count(*) > 1
Order by Count(*);
pause

34. Assignment 8 Due Friday, April 6 Should work for any table instance
Run against my tables
Should insert more records to test
(Don’t include insert commands!)
Example
Quiz 3
Hands-On
Wednesday, April 7
Create Script file to
Drop tables
Create tables
Column/Table constraints
Insert records

35. Quiz 3
Wednesday, April 11
Run Script file to Drop/Create tables, insert records
Create Script file to query database
Hands-on: in Lab 206
D2L