Database Systems Fall Semester, 2008 Instructors: Winston Hsu, Hao-hua Chu. Assignment 1: ER Model and Relational Model (Chapter 2, 3) address_string

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1 Database Systems Fall Semester, 2008 Instructors: Winston Hsu, Hao-hua Chu Assignment 1: ER Model and Relational Model (Chapter 2, 3) Solutions ( 註 : 在畫 ER diagram 中, 有些問題問的比較模糊, 故可做一些假設, 不同的假設可能得出來的答案不同, 以下只供參考 ) Chapter 2 <1> ( 結合 <4> 的答案 ) Each musician that records at Notown has an SSN, a, an address, and a phone number. Poorly paid musicians often share the same address, and no address has more than one phone. SSN address_string musician live address phone CREATE TABLE musician { SSN INTEGER, CHAR(50), PRIMARY KEY(SSN) } CREATE TABLE address { phone CHAR(20), address_string CHAR(100), PRIMARY KEY(phone) } CREATE TABLE live { SSN INTEGER,

2 } phone CHAR(20), PRIMARY KEY(SSN,phone), FOREIGN KEY(SSN) REFERENCES musician(ssn), FOREIGN KEY(phone) REFERENCES address(phone) Each instrument used in songs recorded at Notown has a (e.g., guitar, synthesizer, flute) and a musical key (e.g., C, B-flat, E-flat). instrumentid instrument musical_key 題目中沒有說明 instrument 的 primary key 是什麼, 因此為了要確定每個 instrument 的唯一性, 在此假設每個 instrument 都一個唯一的 instrumentid CREATE TABLE instrument{ instrumentid INTEGER, musical_key CHAR(10), CHAR(30), PRIMARY KEY(instrumentId) } Each album recorded on the Notown label has a title, a copyright date, a format (e.g., CD or MC), and an album identifier.

3 title copyrightdate format album identifier CREATE TABLE album{ identifier INTEGER, SSN INTEGER NOT NULL, title CHAR(20), copyrightdate TIMESTAMP, format CHAR(20); PRIMARY KEY(identifier), FOREIGN KEY (SSN) REFERENCES musician(ssn) } ( 在這裡已經結合了最後的小題的答案 ) Each song recorded at Notown has a title and an author. title song author songid 跟上面的 instrument 一樣, 在此假設每個 song 都有唯一的 songid CREATE TABLE song{ songid INTEGER, title CHAR(20), author CHAR(20), PRIMARY KEY(songId)

4 } Each musician may play several instruments, and a given instrument may be played by several musicians. musician play instrument CREATE TABLE play_instrument{ SSN INTEGER, instrumentid INTEGER, PRIMARY KEY(SSN,instrumentId), FOREIGN KEY (SSN) REFERENCES musician(ssn), FOREIGN KEY (instrumentid) REFERENCES instrument(instrumentid) } Each album has a number of songs on it, but no song may appear on more than one album. album appear song CREATE TABLE appear_song { songid INTEGER, identifier INTEGER, PRIMARY KEY(songId), FOREIGN KEY(identifier) REFERENCES album(identifier), FOREIGN KEY(songId) REFERENCES song(songid) } Each song is performed by one or more musicians, and a musician may perform a number of songs.

5 song perform musician 無法用基本的 SQL 表示 song 至少出現一次在 perform relationship Each album has exactly one musician who acts as its producer. A musician may produce several albums, of course. musician produce album 請看上面的 album

6 把上面所有圖連起來 : SSN address_string phone musician live address produce copyrightdate format play album identifier perform title appear song title instrument musical_key songid author instrumentid

7 <2> The Prescriptions-R-X chain of pharmacies has offered to give you a free lifetime supply of medicine if you design its database. Given the rising cost of health care, you agree. Here's the information that you gather: Patients are identified by an SSN, and their s, addresses, and ages must be recorded. patient SSN age address Doctors are identified by an SSN. For each doctor, the, specialty, and years of experience must be recorded. SSN doctor specialty years_of_e xperience

8 Each pharmaceutical company is identified by and has a phone number. company phone_number For each drug, the trade and formula must be recorded. Each drug is sold by a given pharmaceutical company, and the trade identifies a drug uniquely from among the products of that company. If a pharmaceutical company is deleted, you need not keep track of its products any longer. trade_ drug make company formula 這裡要假設不同的 company 會製造出具有相同 trade_ 的 drug, 則 trade_ 會變成一個 partial key, 如果是假設所有的公司製造出的 drug 的 trade_ 都完全不同, 則 trade_ 就可以變成是 drug 中的 primary key Each pharmacy has a, address, and phone number.

9 假設每個 pharmacy 都有唯一的 pharmcyid pharmacyid pharmacy address phone_number Every patient has a primary physician. Every doctor has at least one patient. patient primary_physicain doctor Each pharmacy sells several drugs and has a price for each. A drug could be sold at several pharmacies, and the price could vary from one pharmacy to another.

10 pharmacy sell drug price Doctors prescribe drugs for patients. A doctor could prescribe one or more drugs for several patients, and a patient could obtain prescriptions from several doctors. Each prescription has a date and a quantity associated with it. You can assume that, if a doctor prescribes the same drug for the same patient more than once, only the last such prescription needs to be stored. quantity patient prescribe doctor date Pharmaceutical companies have long-term contracts with pharmacies. A pharmaceutical company can contract with several pharmacies, and a pharmacy can contract with several pharmaceutical companies. For each contract, you have to store a start date, an end date,and the text of the contract.

11 text start_date company contract pharmacy end_date Pharmacies appoint a supervisor for each contract. There must always be a supervisor for each contract, but the contract supervisor can change over the lifetime of the contract. company contract pharmacy supervisor 1. Draw an ER diagram that captures the preceding information. Identify any constraints not captured by the ER diagram. 把上面的圖全部連起來 :

12 date quantity specialty prescribe SSN SSN doctor primary_physicain patient years_of_experience age address trade_ formula price drug make sell text start_date company pharmacy contract phone_number pharmacyid end_date supervisor address phone_number

13 2. How would your design change if each drug must be sold at a fixed price by all pharmacies? price 會變成 drug 的 attribute, 即 pharmacy sell drug price 3. How would your design change if the design requirements change as follows: If a doctor prescribes the same drug for the same patient more than once, several such prescriptions may have to be stored 改變如下 : id quantity prescriptions date patient prescribe doctor Chapter 3 <3> Answer each of the following questions briefly. The questions are based on the following relational schema: Emp( eid: integer, e: string, age: integer, salary: real) Works( eid: integer, did: integer, pct_time: integer) Dept(did: integer, d: string, budget: real, managerid: integer) 1. Give an example of a foreign key constraint that involves the Dept relation. What are the options for enforcing this constraint when a user attempts to delete a Dept tuple? Eg. CREATE TABLE Works{

14 eid INTEGER, did INTEGER, pct_time INTEGER, PRIMARY KEY(eid,did), FOREIGN KEY(eid) REFERENCES Emp(eid) FOREIGN KEY(did) REFERENCES Dept(did) } Four options : NO ACTION, CASCADE, SET DEFAULT, SET NULL 2. Write the SQL statements required to create the preceding relations, including appropriate versions of all primary and foreign key integrity constraints. CREATE TABLE Emp ( eid INTEGER, e CHAR(50), age INTEGER, salary REAL, PRIMARY KEY(eid) ) CREATE TABLE Works( eid INTEGER, did INTEGER, pct_time INTEGER, PRIMARY KEY(eid,did), FOREIGN KEY (eid) REFERENCES Emp(eid) ON DELETE CASCADE, FOREIGN KEY (did) REFERENCES Dept(did) ON DELETE CASCADE ) CREATE TABLE Dept( did INTEGER, d CHAR(20), budget REAL, managerid INTEGER, PRIMARY KEY(did), FOREIGN KEY(managerid) REFERENCES Emp(eid) ON DELETE SET NULL )

15 3. Define the Dept relation in SQL so that every department is guaranteed to have a manager. CREATE TABLE Dept( did INTEGER, d CHAR(20), budget REAL, managerid INTEGER NOT NULL, PRIMARY KEY(did), FOREIGN KEY(managerid) REFERENCES Emp(eid) ) 4. Write an SQL statement to add John Doe as an employee with eid = 101, age = 32 and salary = 15,000. INSERT INTO Emp VALUES (101, John Doe,32,15000) 5. Write an SQL statement to give every employee a 10 percent raise. UPDATE Emp E SET E.salary = E.salary* Write an SQL statement to delete the Toy department. Given the referential integrity constraints you chose for this schema, explain what happens when this statement is executed. DELETE FROM Dept D WHERE D.d = Toy <4> 請看 <1>