PESIT Bangalore South Campus

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1 Fifth Semester B.E. IA Test-I, 2014 USN 1 P E I S PESIT Bangalore South Campus (Hosur Road, 1KM before Electronic City, Bangalore ) Department of Information Science & Engineering Section: 5 ISE A & B Max Marks: 50 Subject & code: Database Management Systems Time: 90 Mins. Name of faculty: Mrs Divya Naikwadi Date: Solution Set 1. Explain the main characteristics of a Data base approach. a) Self describing nature of a database system: The database system contains not only the database itself but also complete definition of database structure and constraints. Whenever a request is made to access name of student file then DBMS software refers to the catalog to determine the structure of the student file and position and size of the name data item. b) Insulation between programs and data and data abstraction: In traditional file processing, if changes are made in the structure of a file then it may require changing all the programs that access file. The data files are stored separately from the access programs and this property is called program data independence The characteristics that allow program data independence and program operation independence is called data abstraction. c) Support of multiple views of the data: A database will have no. of users each of whom will require different perspective or view of the database. A view is a subset of database and is derived from base tables but is not explicitly stored. d) Sharing of data and multiuser transaction processing: The DBMS must include concurrency control to ensure that several users trying to update the same data in a controlled manner. This is used in Online Transaction Processing applications. Transactions must enforce Atomicity, consistency, isolation and durability (ACID property) 2. With a neat diagram explain the different component modules of a DBMS

2 A DBMS is a complex software system. The figure is divided into two halves. The top half of the figure refers to the various users of the database environment and their interfaces. The lower half shows the internal of the DBMS responsible environment for the storage of data and processing of transactions. In top half DDL data definition language) compiler processes schema def specified in DDL and stores description of schemas in DBMS catalog. All the priviledged commands to check the login and accessing priviledges of the user will be processed by DBA processor. Casual users and persons with occasional need for information will use interactive interface. These queries are parsed and analyzed for correctness of operations by query compiler. Query optimizer will rearange and possible reordering of operations, elimination of redundancies and use of correct algo. Application programmers write programs in host language that are submitted to precompiler and precompiler extracts DML commands from an application program and these commands are sent to DML compiler for compilation into object code for database access. Rest of the program is sent to host language complier. The object code and DML commands are linked forming canned transactions whose executable codes includes calls to runtime database processor. The lower half has runtime database processor to execute priviledged commands, query plans and canned transactions. It works with catalog and may update it with statistics. It works with stored data manager which in turn uses basic O.S services and performs operations on stored databases. Also concurrency control, backup and recovery systems are performed

3 separately. 3. Explain the following terms a)weak Entity : Entity type that do not have key attributes of their own are called weak entity type for eg: dependent entity has three attributes name, sex, birth date, among these no attribute is key attribute and name is partial key so Dependent is a weak entity type.

4 b)partial key :Partial key is in the weak entity set, which is a set of attributes that can uniquely identify weak entities that are related to the same owner entity. For eg: In dependent entity with name, sex, birth date as entities,we take name as a partial key of the dependent entity. c)schema The description of a database. Includes descriptions of the database structure and the constraints that should hold on the database. This is formed at the database design phase d)participation constraint The participation constraint specifies whether the existence of an entity depends on it being related to another entity through the relationship type.it specifies the minimum no. of instances that each entity can participate in and hence is also called the minimum cardinality constraint. For eg: If a company states that every employee must work for a department then an employee entity can exist only if it participates in WORKS_FOR. this is called as the total participation of EMPLOYEE in WORKS_FOR Total participation EMPLOYEE WORK S_FOR DEPARTMENT Cardinality ratio e)composite attribute The attribute may be composed of several components, which represent more basic attributes with independent meanings For example, Address (Apt#, House#, Street, City, State, ZipCode, Country) or Name (FirstName, MiddleName, LastName). Composition may form a hierarchy where some components are themselves composite.

5 The value of a composite attribute is the concatenation of the values of its constituent simple attributes. 4. With a neat diagram explain the Three schema architecture The Goal of three schema architecture is to separate the user applications and the physical database. Defines DBMS schemas at three levels: Internal schema at the internal level to describe physical storage structures and access paths. Typically uses a physical data model. Conceptual schema at the conceptual level to describe the structure and constraints for the whole database for a community of users. Uses an implementation data model. External schemas at the external level to describe the various user views. Usually uses the same data model as the conceptual level. It describes the part of the db that a particular user group is interested in and hides the rest of the db from that user group. Mappings among schema levels are needed to transform requests and data. Programs refer to an external schema, and are mapped by the DBMS to the internal schema for execution. 5. SonyMusic has decided to store in a database, information on the musicians who perform for its albums. The information provided is as follows:

6 Each musician who records at this company has an ID, a name, an address and a phone no. Each instrument that is used in the songs has a name(eg: guitar, flute, drums) and a musical key (eg: C, B-flat,E-flat) Each album that is recorded on the company label has a title, a copy right date, a format (eg: CD or MC) and an album identifier Each song recorded at the company has a title and an author Each musician may play several instruments and several musicians may play a given instrument Each album has number of songs on it, but no song may appear in more than one album One or more musicians perform each song, and a musician may perform in a number of songs Each album has exactly one musician who acts as its producer. A musician may produce several albums. Draw an ER diagram for the SonyMusic company database. As discussed in the class 6. Consider a Movie Database with the following relations Movie(id#, name, date_of_release, revenue) Actor(fname, lname, phone, movie_name, dob) Director(name, dob, movie_name) ProductionCompany(name, addr, city) a) Retrieve the details of the movies released prior to 2008 which crossed over a 100 crore SELECT * FROM MOVIE WHERE DATE_OF_RELEASE< AND REVENUE > ; b) List out all the Production companies situated in Mumbai, Delhi and Bangalore SELECT NAME FROM PRODUCTIONCOMPANY WHERE CITY IN ( MUMBAI, DELHI, BANGALORE ); c) Remove the attribute phone and Add an attribute Address in its place in the Actor entity ALTER TABLE ACTOR DROP PHONE; ALTER TABLE ACTOR ADD ADDRESS VARCHAR(30) AFTER LNAME; d) Add a new attribute Acted-in to the entity Director and make sure that already existing directors data in Acted-in attribute is None ALTER TABLE DIRECTOR ADD ACTED_IN VARCHAR(20); UPDATE DIRECTOR SET ACTED_IN= NONE ; e) Display the total number of actors stored in the Movie database SELECT COUNT(*) FROM ACTOR;

PESIT Bangalore South Campus

PESIT Bangalore South Campus INTERNAL ASSESSMENT TEST I Date : 18/08/2015 Max Marks : 50 Subject & Code : Data Base Management System(10CS54) Section : 5 th Sem A & B Name of faculty : Ms.Rashma.B.M Time : 11:30am to 1:00pm Note: