The appendix contains information about the Classic Models database. Place your answers on the examination paper and any additional paper used.

Transcription

1 Name: Student Number: Instructions: Do all 9 questions. There is a total of 87 marks. The appendix contains information about the Classic Models database. Place your answers on the examination paper and any additional paper used. At the end of the examination hand in the exam paper with your answers. 1

2 1. (5) Answer the following: a) What do the following acronyms stand for: RI, EERD, BCNF. b) Who was the first to develop a notation for ERDs. c) Who is credited with inventing relational databases. 2

3 2. (5) Consider the Customers, Orders, and Payments table in the ClassicModels database. Each table is in BCNF. The Customers table has one row per customer. The Orders table has one row for each order. The Payments table has one row for each payment made by a customer. Note that Payments has a composite primary key and that checknumber is not unique. Consider the table XXX created using: /* create XXX */ create table XXX ( `customernumber` int(11) NOT NULL, `customername` varchar(50) NOT NULL, `ordernumber` int(11) NOT NULL, `status` varchar(15) NOT NULL, `checknumber` varchar(50) NOT NULL, `amount` double NOT NULL) /* Data to be inserted */ select customers.customernumber, customername, orders.ordernumber, status, checknumber, amount from customers inner join orders on (customers.customernumber = orders.customernumber) inner join payments on (customers.customernumber = payments.customernumber) ; /* Set primary key */ alter table XXX add primary key( `ordernumber`, `checknumber` ); a) What are the functional dependencies in XXX? b) With reference to the functional dependencies, explain why XXX is not BCNF. 3

4 3. (5) Consider students at UW; students are uniquely identified by their student number. Suppose the university gathers information about each student: Languages spoken License plate numbers of cars they will drive to school. Clearly the above two pieces of information are clearly independent of one another a language spoken by a student is not at all related to any car they drive. Now suppose someone creates a table create table Students ( `studentnumber` int(7) NOT NULL, `language` varchar(50) NOT NULL, `license` varchar (7) NOT NULL); alter table Students add primary key( `studentnumber`,`language`, `license`); a) If student 123 speaks English and French and drives two cars with license plate numbers ABC 123 and XYZ 999, show the rows that should exist in the table Students. b) Is Students in 4NF? c) If your answer is no to part b), then explain why not, and show a lossless decomposition to create 4NF tables. 4

5 4. (12) Consider the ClassicModels database. Write SQL queries to: a) List the first names of employees who have handled an order that included products from 5 different product lines. b) List the first name of an employee who is not located in the same office as the person they report to. c) List the names of customers where their payment total exceeds $1,000,000. 5

6 5. (8) Consider the ClassicModels database. a) Consider the SQL statement: select city from Offices where state = "CA"; Translate the SQL statement into a sequence of relational algebra statements. b) Consider the SQL statement: select city, amount from customers inner join orders on (customers.customernumber = orders.customernumber) inner join payments on (customers.customernumber = payments.customernumber) where city = "NYC" and status = "shipped" ; Illustrate a relational algebra query tree for the execution of the statement. 6

7 6. (20) Consider the following EER model 7

8 a) Map the EER model to a relational database using the principles covered in the course. Clearly show for each table, its primary key, foreign keys (and what they reference), and other attributes. Create separate tables for each supertype and each subtype. 8

9 b) Given that one implements the database without check constraints or special purpose procedures/triggers it is possible the database can become corrupted. For example, some party could be both an person and an organization, or, a party could be both the buyer and seller of the same contract. i. Write a SQL Select statement to list any party that is both a person and an organization. ii. Write a SQL Select statement to list the name of any party that is both the buyer and the seller for the same contract. 9

10 7. (20) Every database management system needs an Information Schema database. Consider the following from MySQL sources: INFORMATION_SCHEMA provides access to database metadata. Metadata is data about the data, such as the name of a database or table, or the data type of a column. Other terms that sometimes are used for this information are data dictionary and system catalog. INFORMATION_SCHEMA is the information database, the place where information about all the other databases that the MySQL server maintains is stored. In a local instance of MySQL the following queries were run: Sample query use information_schema; select table_name from tables where table_schema = "classicmodels"; use information_schema; select count(*) from tables; Result Customers Employees Offices Orderdetails Orders Payments Productlines Products 197 use information_schema; select count(*) from columns where table_schema = "classicmodels"; 59 The INFORMATION_SCHEMA provides information that one can query to get information about primary keys, foreign keys, columns, tables, etc. For instance, using the INFORMATION_SCHEMA we must be able to run queries such as the above, or to list: The primary key of table X The foreign keys in table X The table referenced by foreign key Y in table X The names and data types of columns in table X Draw an ER (or an EER) model for an INFORMATION_SCHEMA. Your design must include: database names and owners, table names, column names (and their data types), primary keys, foreign keys (but not rules such as on delete or on update, etc). You must include entity types: table, column, attribute, and others as deemed necessary. 10

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12 8. (6) Consider the following Linear Hash file that currently has 4 records stored in 4 buckets. Each primary area bucket can hold 2 records. Suppose the hash functions that are used with this file are h i (key) = key mod 2 i, where i = 0, 1, 2, 3, 4 Note that some useful hash values are given below. Overflows are handled through chaining. Assume each overflow bucket can hold one record. The splitting policy for this file is to split a bucket after 2 insertions have been performed. That is, there is a split after every other insertion. Assume the file has just finished a full expansion and so the split pointer points to bucket 0. Our starting point is this file of 4 buckets (for simplicity we only show key values) : Split Pointer Show the file and its records after the following keys (records) have been inserted: 44, 77, 88, 100 Show each bucket and its contents, overflow buckets, and the split pointer. To show your work you could illustrate the file each time a bucket splits. key Mod 2 0 key Mod 2 1 key Mod 2 2 key Mod 2 3 key Mod 2 4 Key key Mod 1 key Mod 2 key Mod 4 key Mod 8 key Mod

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14 9. (6) Consider the following b+-tree where leaf nodes can hold at most 5 keys and internal nodes can hold at most 4 keys. Not shown below is the fact that each key in a leaf is accompanied by a pointer to a record stored elsewhere. Consider that 6 records are inserted into the file. The keys of the records to be inserted are: 25, 27, 65, 67, 105, a) Illustrate the b+-tree after records with keys 25 and 27 are inserted. 14

15 b) Illustrate the b+-tree after records with keys 65 and 67 are inserted. 15

16 c) Illustrate the b+-tree after records with keys 105 and 107 are inserted. 16

17 Appendix Notes added Dec 5, 2016: In Fall 2015 the students were very familiar with this database. Below is a diagram that shows PKs and includes FKs (e.g. productline in products, productcode in orderdetails) Note that is not Chen notation, but it does indicate a one-to-many relationship. Note that PKs are shown with a Key symbol. 17