CS348 INFORMATION SYSTEMS

Transcription

1 CS348 INFORMATION SYSTEMS Romila Pradhan Advanced SQL

2 Logistics

3 Connecting to CS Oracle Server Registered for CS348 You should have an account on Oracle at Purdue. Login details: Connecting to Oracle: You need to edit the following file: - (sh/ksh/bash) ~/.profile - (csh/tcsh) ~/.login

4 Connecting to CS Oracle Server Once connected, you can change password: SQL> password Things to note: - Do NOT in your password (locks out) - Easy to remember password - Bothersome for the IT Staff to address each student s account (locked out/forgotten details)

5 Today s PSO: Setup

6 Example Database Consider a music database: MUSICIAN (MNO, NAME, ADDRESS, PHONE) ALBUM (ANO, ATITLE, COPYRIGHT_DATE, MNO, COPY_SOLD) SONG (SNO, STITLE, ANO, LYRICIST) PLAY (MNO, INSTRUMENT) PERFORM (MNO, SNO, INSTRUMENT)

7 Example Database Consider a music database: MUSICIAN (MNO, NAME, ADDRESS, PHONE) ALBUM (ANO, ATITLE, COPYRIGHT_DATE, MNO, COPY_SOLD) SONG (SNO, STITLE, ANO, LYRICIST) PLAY (MNO, INSTRUMENT) PERFORM (MNO, SNO, INSTRUMENT)

8 Foreign Keys ALBUM (ANO, ATITLE, COPYRIGHT_DATE, MNO, COPY_SOLD) CREATE TABLE Album( ANO INTEGER, ATITLE VARCHAR(24), COPYRIGHT_DATE DATE, MNO INTEGER, COPY_SOLD INTEGER, PRIMARY KEY (ANO), FOREIGN KEY (MNO) REFERENCES Musician (MNO) );

9 Load Data - Exit sqlplus SQL> exit - Create file with insert commands Download and save sample data from the following link: - Log in to sqlplus and run the script (use appropriate path of file)

10 Check Database - View the relations you created: SQL> SELECT TABLE_NAME FROM USER_TABLES;

11 Check Database - View the relations you created: SQL> SELECT TABLE_NAME FROM USER_TABLES; TABLE_NAME ALBUM MUSICIAN PERFORM PLAY SONG

12 Aggregated Data

13 Aggregated Data: Group Functions Group functions operate on sets of rows to give one result per group. e.g., - Count the number of songs that each musician has performed - Count the number of songs in an album

14 Aggregated Data: Group Functions Query construct SELECT [column,] group_function (on certain columns) FROM table [WHERE condition] [GROUP BY group_by_expression]

15 Aggregated Data: Group Functions Query construct SELECT [column,] group_function (on certain columns) FROM table [WHERE condition] [GROUP BY group_by_expression] group_functions: SUM, AVG, COUNT, MAX, MIN group_by_expression: columns

16 Aggregated Data: Group Functions Query construct SELECT [column,] group_function (on certain columns) FROM table [WHERE condition] [GROUP BY group_by_expression] Columns in SELECT list that are not in group functions must be in the GROUP BY clause

17 Aggregated Data: Group Functions Query construct SELECT A, B, C, group_function (on B) FROM table [WHERE condition] [GROUP BY A, C] Columns in SELECT list that are not in group functions must be in the GROUP BY clause

18 Aggregated Data: Group Functions General query construct SELECT [column,] group_function (on certain columns) FROM table [WHERE condition] [GROUP BY group_by_expression] [HAVING group_condition] [ORDER BY column];

19 Query 1 (GROUP BY) Count the number of songs that each musician has performed.

20 Query 1 (GROUP BY) Count the number of songs that each musician has performed. SELECT MNO, Count(SNO) FROM Perform GROUP BY MNO;

21 Query 1 (GROUP BY) Count the number of songs that each musician has performed. SELECT MNO, Count(SNO) FROM Perform GROUP BY MNO; MNO COUNT(SNO)

22 Query 2 (GROUP BY) Count the number of songs in an album.

23 Query 2 (GROUP BY) Count the number of songs in an album. SELECT ANO, Count(SNO) FROM Song GROUP BY ANO;

24 Query 2 (GROUP BY) Count the number of songs in an album. SELECT ANO, Count(SNO) FROM Song GROUP BY ANO; ANO COUNT(SNO)

25 Query 2 (GROUP BY + ALIAS) Count the number of songs in an album. SELECT ANO, Count(SNO) AS NumOfSongs FROM Song GROUP BY ANO; ANO NumOfSongs

26 Query 2 (GROUP BY + Sorting) Count the number of songs in an album. Sort the result set by the number of songs in an album in a descending order. SELECT ANO, Count(SNO) AS NumOfSongs FROM Song GROUP BY ANO ORDER BY NumOfSongs DESC; ANO NumOfSongs

27 Query 3 (Limit group results) Count the number of songs in an album. Display the top 5 albums having the most number of songs

28 Query 3 (Limit group results) Count the number of songs in an album. Display the top 5 albums having the most number of songs SELECT ANO, NumOfSongs FROM (SELECT ANO, Count(SNO) AS NumOfSongs FROM Song GROUP BY ANO ORDER BY NumOfSongs DESC) WHERE ROWNUM <= 5; ANO NumOfSongs

29 Query 4 (Filter group results) Identify albums that have more than 3 songs.

30 Query 4 (Filter group results) Identify albums that have more than 3 songs. SELECT ANO, Count(SNO) AS NumOfSongs FROM Song GROUP BY ANO HAVING Count(SNO)>3; ANO NumOfSongs

31 Query 4 (Filter group results) Identify albums that have more than 3 songs. SELECT ANO, Count(SNO) AS NumOfSongs FROM Song GROUP BY ANO HAVING Count(SNO)>3; - filters the result set of GROUP BY - (therefore,) requires GROUP BY - (different from WHERE which applies to individual records)

32 Query 5 List the number of albums produced and the average number of copies sold by each musician.

33 Query 5 List the number of albums produced and the average number of copies sold by each musician. SELECT MNO, Count(*) AS Num_Albums, AVG(COPY_SOLD) AS Avg_Sales FROM Album GROUP BY MNO; MNO NUM_ALBUMS AVG_SALES

34 Joins

35 Joins Retrieve data from multiple tables

36 Joins Retrieve data from multiple tables Joins No Join Clause Implicit Join Clause Explicit Join Clause Cross Join Natural Join Outer Join Inner Join Left Outer Join Right Outer Join Full Outer Join

37 View of the data AVIEW ANO ATITLE MNO 1 Parachutes 1 2 A Rush of Blood 1 3 XY 3 MVIEW MNO NAME 1 Chris Martin 2 Jonny Buckland 3 Guy Berryman CREATE VIEW AVIEW AS SELECT ANO, ATITLE, MNO FROM Album WHERE ANO BETWEEN 1 AND 3; CREATE VIEW MVIEW AS SELECT MNO, NAME FROM Musician WHERE MNO BETWEEN 1 AND 3;

38 No Join Clause CROSS JOIN - Cartesian Product AVIEW ANO ATITLE MNO 1 Parachutes 1 2 A Rush of Blood 1 3 XY 3 MVIEW MNO NAME 1 Chris Martin 2 Jonny Buckland 3 Guy Berryman ANO TITLE MNO MNO NAME 1 Parachutes 1 1 Chris Martin SELECT * FROM AVIEW CROSS JOIN MVIEW; 1 Parachutes 1 2 Jonny Buckland 1 Parachutes 1 3 Guy Berryman 2 A Rush of Blood 1 1 Chris Martin 2 A Rush of Blood 1 2 Jonny Buckland 2 A Rush of Blood 1 3 Guy Berryman 3 XY 3 1 Chris Martin 3 XY 3 2 Jonny Buckland 3 XY 3 3 Guy Berryman

39 No Join Clause AVIEW CROSS JOIN ANO ATITLE MNO 1 Parachutes 1 2 A Rush of Blood 1 3 XY 3 MVIEW MNO NAME 1 Chris Martin 2 Jonny Buckland 3 Guy Berryman SELECT * FROM AVIEW CROSS JOIN MVIEW WHERE AVIEW.MNO=MVIEW.MNO; ANO TITLE MNO MNO NAME 1 Parachutes 1 1 Chris Martin 2 A Rush of Blood 1 1 Chris Martin 3 XY 3 3 Guy Berryman

40 Implicit Join Clause NATURAL JOIN - based on common columns AVIEW ANO ATITLE MNO 1 Parachutes 1 2 A Rush of Blood 1 3 XY 3 MVIEW MNO NAME 1 Chris Martin 2 Jonny Buckland 3 Guy Berryman SELECT * FROM AVIEW NATURAL JOIN MVIEW; MNO ANO TITLE NAME 1 1 Parachutes Chris Martin 1 2 A Rush of Blood Chris Martin 3 3 XY Guy Berryman

41 Explicit Join Clause INNER JOIN - explicitly specify join condition - useful when >1 common columns AVIEW ANO ATITLE MNO 1 Parachutes 1 2 A Rush of Blood 1 3 XY 3 MVIEW MNO NAME 1 Chris Martin 2 Jonny Buckland 3 Guy Berryman SELECT * FROM AVIEW INNER JOIN MVIEW ON AVIEW.MNO=MVIEW.MNO; ANO TITLE MNO MNO NAME 1 Parachutes 1 1 Chris Martin 2 A Rush of Blood 1 1 Chris Martin 3 XY 3 3 Guy Berryman

42 Explicit Join Clause LEFT OUTER JOIN - preserves unmatched rows in LEFT table AVIEW ANO ATITLE MNO 1 Parachutes 1 2 A Rush of Blood 1 3 XY 3 4 TempAlbum 4 MVIEW MNO NAME 1 Chris Martin 2 Jonny Buckland 3 Guy Berryman SELECT * FROM AVIEW LEFT OUTER JOIN MVIEW ON AVIEW.MNO=MVIEW.MNO; ANO TITLE MNO MNO NAME 1 Parachutes 1 1 Chris Martin 2 A Rush of Blood 1 1 Chris Martin 3 XY 3 3 Guy Berryman 4 TempAlbum 4

43 Explicit Join Clause RIGHT OUTER JOIN - preserves unmatched rows in RIGHT table AVIEW ANO ATITLE MNO 1 Parachutes 1 2 A Rush of Blood 1 3 XY 3 4 TempAlbum 4 MVIEW MNO NAME 1 Chris Martin 2 Jonny Buckland 3 Guy Berryman SELECT * FROM AVIEW RIGHT OUTER JOIN MVIEW ON AVIEW.MNO=MVIEW.MNO; ANO TITLE MNO MNO NAME 1 Parachutes 1 1 Chris Martin 2 A Rush of Blood 1 1 Chris Martin 3 XY 3 3 Guy Berryman 2 Jonny Buckland

44 Explicit Join Clause FULL OUTER JOIN - preserves unmatched rows in BOTH tables AVIEW ANO ATITLE MNO 1 Parachutes 1 2 A Rush of Blood 1 3 XY 3 4 TempAlbum 4 MVIEW MNO NAME 1 Chris Martin 2 Jonny Buckland 3 Guy Berryman SELECT * FROM AVIEW FULL OUTER JOIN MVIEW ON AVIEW.MNO=MVIEW.MNO; ANO TITLE MNO MNO NAME 1 Parachutes 1 1 Chris Martin 2 A Rush of Blood 1 1 Chris Martin 3 XY 3 3 Guy Berryman 2 Jonny Buckland 4 TempAlbum 4

45 Joins Joins No Join Clause Implicit Join Clause Explicit Join Clause Cross Join Natural Join Outer Join Inner Join Left Outer Join Right Outer Join Full Outer Join

46 Sample Queries

47 Queries 1. Find the phone numbers of all musicians who had used 'Guitar' to perform. 2. Find the ANOs of the albums which have a song performed by 'Guitar'. 3. Find the names of the musicians who have performed for albums that have a copyright before '03-Sep-1999'. 4. Find the name of the musician who has the album with the maximum number of sold copies. 5. Find the MNO of the musician who produces the largest number of albums.

48 Queries 6. Find ANOs of the albums that have a song performed by other musicians (not the producer). 7. Get names of the musicians who cannot play 'Piano'. 8. Get names of the musicians who only use 'Piano' or 'Guitar' to perform. 9. Get ANOs of the albums which only have songs performed by 'Guitar'. 10. Get names of the musicians who can play only one instrument. 11. Get names of the musicians who have never performed a song produced by other musicians.