Chapter 5 SQL

Agenda Data Manipulation Language (DML) –SELECT –Union compatible operations –Update database

SQL DML - SELECT SELECT [DISTINCT|ALL] {* | [col- expr [AS newname]][,...] FROM table-name [alias] [,...] [WHERE condition] [GROUP BY colm [, colm] [HAVING condition]] ORDER BY colm [, colm]

SQL DML - SELECT SELECT attributes (or calculations: +, -, /, *) FROM relation SELECT DISTINCT attributes FROM relation

Examples SELECT stuname FROM student; SELECT stuid, stuname, credit FROM student; SELECT stuid, stuname, credit+10 FROM student; SELECT DISTINCT major FROM student;

SQL DML - SELECT SELECT attributes (or * wild card) FROM relation WHERE condition

Examples SELECT * FROM student; SELECT stuname, major, credit FROM student WHERE stuid = ‘S114’; SELECT * FROM faculty WHERE dept = ‘MIS’;

SELECT - WHERE condition AND OR NOT IN NOT INBETWEEN IS NULLIS NOT NULL SOMEALL LIKE '%' multiple characters LIKE ‘_’ single character

Examples SELECT * FROM faculty WHERE dept = ‘MIS’ AND rank = ‘full professor’; SELECT * FROM faculty WHERE dept = ‘MIS’ OR rank = ‘full professor’; SELECT * FROM faculty WHERE dept = ‘MIS’ NOT rank = ‘full professor’;

SELECT * FROM class WHERE room LIKE ‘B_S%’; SELECT * FROM class WHERE room NOT LIKE ‘BUS%’; SELECT productid, productname FROM inventory WHERE onhand BETWEEN 50 and 100;

SELECT companyid, companyname FROM company WHERE companyname BETWEEN ‘G’ AND ‘K’; SELECT productid, productname FROM inventory WHERE onhand NOT BETWEEN 50 and 100; SELECT companyid, companyname FROM company WHERE companyname NOT BETWEEN ‘G’ AND ‘K’;

SELECT facname FROM faculty WHERE dept IN (‘MIS’, ‘ACT’); SELECT facname FROM faculty WHERE rank NOT IN (‘assistant’, ‘lecture’); SELECT customername FROM customer WHERE add IS NOT NULL;

SELECT customername FROM customer WHERE creditlimit IS NULL;

SELECT - aggregate functions COUNT (*) COUNT SUM AVG MIN MAX

Examples SELECT COUNT(*) FROM student; SELECT COUNT(major) FROM student; SELECT COUNT(DISTINCT major) FROM student;

SELECT COUNT(stuid), SUM(credit), AVG(credit), MAX(credit), MIN(credit) FROM student;

How many different guests have made bookings for August 2004? Hotel (hotelno, hotelname, city) Room (roomno, hotelno, type, price) Booking (hotelno, guestno, datefrom, dateto, roomno) Guest (guestno, guestname, guestaddress)

How many different guests have made bookings for August 2004? SELECT COUNT(DISTINCT guestno) FROM booking WHERE (datefrom <= ‘8/31/04’) AND (dateto >= ‘8/1/04’);

SELECT - GROUP GROUP BY HAVING

Examples SELECT major, AVG(credit) FROM student GROUP BY major SELECT course#, COUNT(stuid) FROM enrollment GROUP BY course#

Examples SELECT major, AVG(credit) FROM student GROUP BY major HAVING COUNT(*) > 2; SELECT course#, COUNT(stuid) FROM enrollment GROUP BY course# HAVING COUNT(*) > 2;

SELECT major, AVG(credit) FROM student WHERE major IN (‘mis’, ‘act’) GROUP BY major HAVING COUNT(*) > 2;

SELECT - ORDER BY ORDER BY ORDER BY... DESC

Examples SELECT facname, rank FROM faculty ORDER BY facname; SELECT facname, rank FROM faculty ORDER BY rank DESC, facname;

SELECT - JOIN Tables Multiple tables in FROM clause MUST have join conditions!!!

Examples SELECT stuname, grade FROM student, enrollment WHERE student.stuid = enrollment.stuid;

SELECT enrollment.course#, stuname, major FROM class, enrollment, student WHERE class.course# = enrollment.course# AND enrollment.stuid = student.stuid AND facid = ‘F114’ ORDER BY enrollment.course#;

OUTER JOINS RIGHT JOIN LEFT JOIN FULL JOIN Appending (+) to the optional column (null) in the join condition (Oracle)

Examples SELECT f.facid, f.facname, c.course# FROM class c, faculty f WHERE c.facid (+) = f.facid ORDER BY f.facname; (rightouterjoin) SELECT s.stuname, major, grade FROM student s, enrollment e WHERE s.stuid = e.stuid (+) ORDER BY s.stuname; (leftouterjoin)

SELECT f.facid, f.facname, c.course# FROM class c RIGHT JOIN faculty f ON c.facid = f.facid ORDER BY f.facname; (rightouterjoin) SELECT s.stuname, major, grade FROM student s LEFT JOIN enrollment e ON s.stuid = e.stuid ORDER BY s.stuname; (leftouterjoin)

SELECT f.facid, f.facname, c.course#, c.room FROM class c, faculty f WHERE c.facid (+) = f.facid (+) ORDER BY f.facname; (fullouterjoin)

SELECT f.facid, f.facname, c.course#, c.room FROM class c FULL JOIN faculty f ON c.facid = f.facid ORDER BY f.facname; (fullouterjoin)

Example List the number of room in each hotel in London. Hotel (hotelno, hotelname, city) Room (roomno, hotelno, type, price) Booking (hotelno, guestno, datefrom, dateto, roomno) Guest (guestno, guestname, guestaddress)

Example List the number of room in each hotel in London. SELECT r.hotelno, COUNT(roomno) FROM room r, hotel h WHERE r.hotelno=h.hotelno AND city = ‘London' GROUP BY hotelno;

Union Compatible Operations UNION MINUS or EXCEPT INTERSECT Union compatible operator [ALL] [CORRESPONGIND][BY column,..] (ALL includes duplicated rows in the result) Used between SELECT commands

Examples SELECT stuid, stuname FROM sacstudent UNION SELECT stuid, stuname FROM chicostudent; SELECT * FROM sacstudent UNION CORRESPONGIND BY stuid, stuname SELECT * FROM chicostudent;

SELECT stuid, stuname FROM sacstudent EXCEPT SELECT stuid, stuname FROM chicostudent; (SELECT stuid, stuname FROM sacstudent) INTERSECT (SELECT stuid, stuname FROM chicostudent) ORDER BY 2;

Column Alias SELECT prodid, prodname, (salesprice - goodofcost) profit FROM product ORDER BY prodid; SELECT prodid, prodname, (salesprice - goodofcost) AS profit FROM product ORDER BY prodid;

SUBQUERY SELECT stuid, stuname, credit FROM student WHERE credit > (SELECT AVG(credit) FROM student);

SELECT stuid, stuname, major FROM student WHERE stuid IN (SELECT stuid FROM enrollment);

SELECT stuid, stuname, major FROM student WHERE stuid NOT IN (SELECT stuid FROM enrollment)

Example What is the most commonly booked room type for all hotels in London? Hotel (hotelno, hotelname, city) Room (roomno, hotelno, type, price) Booking (hotelno, guestno, datefrom, dateto, roomno) Guest (guestno, guestname, guestaddress)

What is the most commonly booked room type for all hotels in London? SELECT type, MAX(y) FROM (SELECT type, COUNT(type) AS y FROM booking b, hotel h, room r WHERE r.roomno = b.roomno AND r.hotelno = b.hotelno AND b.hotelno = h.hotelno AND city = 'London' GROUP BY type) GROUP BY type;

EXIST SELECT s.stuname, major FROM student s WHERE EXIST (SELECT * FROM enrollment e WHERE s.stuid = e.stuid);

NOT EXIST SELECT s.stuname, major FROM student s WHERE NOT EXIST (SELECT * FROM enrollment e WHERE s.stuid = e.stuid);

SOME SELECT stuid, stuname, major, credit FROM student WHERE credit > SOME (SELECT credit FROM student WHERE major=‘mis’);

ANY SELECT stuid, stuname, major, credit FROM student WHERE credit > ANY (SELECT credit FROM student WHERE major=‘mis’);

ALL SELECT stuid, stuname, major, credit FROM student WHERE credit > ALL (SELECT credit FROM student WHERE major=‘mis’);

What is the lost income from unoccupied rooms at the Grosvenor Hotel today? Hotel (hotelno, hotelname, city) Room (roomno, hotelno, type, price) Booking (hotelno, guestno, datefrom, dateto, roomno) Guest (guestno, guestname, guestaddress)

What is the lost income from unoccupied rooms at the Grosvenor Hotel today? SELECT SUM(price) FROM room r, hotel h WHERE r.hotelno = h.hotelno AND h.hotelname = 'Grosvenor’ AND r.roomno NOT IN (SELECT roomno FROM booking b, hotel h WHERE b.hotelno = h.hotelno AND (datefrom <= ‘SYSTEM DATE’ AND dateto >= ‘SYSTEM DATE’) AND h.hotelname = 'Grosvenor');

What is the lost income from unoccupied rooms at each hotel today? Hotel (hotelno, hotelname, city) Room (roomno, hotelno, type, price) Booking (hotelno, guestno, datefrom, dateto, roomno) Guest (guestno, guestname, guestaddress)

What is the lost income from unoccupied rooms at each hotel today? SELECT h.hotelno, SUM(price) FROM room r WHERE roomno NOT EXIST (SELECT * FROM booking b, hotel h, room r WHERE b.hotelno = h.hotelno AND r.roomno = b.roomno AND r.hotelno = b.hotelno AND datefrom <= ‘SYSTEM DATE’ AND dateto >= ‘SYSTEM DATE’ ) GROUP BY hotelno;

SQL DML - UPDATE, INSERT, DELETE INSERT INTO table-name [(colm [, colm])] VALUES (const [, const] ) UPDATE table-name SET colm = expr [colm = expr]... [WHERE condition] DELETE FROM table-name [WHERE condition]

Examples INSERT INTO student (stuid, stuname, major, credit) VALUES (‘S114’, ‘Grace’, ‘MIS’, 60); UPDATE student SET major = ‘Database’, credit = 100 WHERE stuid = ‘S114’; UPDATE student SET major = ‘MIS’;

DELETE FROM student WHERE stuid = ‘S114’; DELETE FROM student;

Points To Remember Data Manipulation Language (DML) –SELECT –Union compatible operations –Update database

Assignment Review chapter 1 – 5, appendix C Read chapter 6 Homework Assignment –5.7 – 5.28 (not 5.18) –Due date: