1. What is a database?
A collection of files storing related data.
A collection of objects storing related data.
A collection of variables storing related data.
A collection of disks storing related data.
2. What means Required Functionality ?
Describe real-world files in terms of stored data
Describe real-world entities in terms of stored data
Describe real-world tables in terms of stored data
None of the above.
3. Database Management System ?
is a software system designed to provide data management services
is a hardware system designed to provide data management services
is a software system designed to provide data restore services
is a hardware system designed to provide data restore services 4. which one of the following is DBMS
Oracle
DB2 (IBM)
SQL Server (Microsoft),
Java
5. What is the definition of a Relation?
Relation is basically a domain of attribute
Relation is basically a collection of attribute
Relation is basically a table with rows & columns
None of the above.
6. Fill in the blanks by the following words (Database schema(1) , Relation instance(2), Database instance (3), Relation schema (4))
……4 ……….describes column heads
……1……….set of all relation schemas
……2……….concrete table content
…………3……….set of all relation instances 7. Integrity constraint?
Condition specified on a database schema
Restricts data that can be stored in db instance
All of the above.
8. Primary key
One candidate key can be selected as primary key.
Two candidate key can be selected as primary key.
One foreign key can be selected as primary key.
None of the above.
9. Foreign Key Constraints
A relation can refer to a tuple in another relation
is a Field that refers to tuples in another relation.
All of the above.
10. Query languages allow manipulation and retrieval of data from a database.
True
false
11. Query Languages is the same as programming languages!
True
false
12. What is true about Query languages?
QLs not expected to be “Turing complete”.
QLs not intended to be used for complex calculations.
QLs support easy, efficient access to large data sets.
None of the above
13. Fill the blanks by Basic operations symbols:( ∪, σ ,−, π ,× )
Selection ( ... ) Selects a subset of rows from relation.
Projection ( ………..…. ) Deletes unwanted columns from relation.
Cross-product ( …………. ) Allows us to combine two relations.
Set-difference ( ………. ) Tuples in reln. 1, but not in reln. 2.
Union ( …………. ) Tuples in reln. 1 and in reln. 2.
14. What is the SQL code for the following relational algebra
Select * from S2;
Select sname, rating from S2;
Select S2 from sname, rating;
None of the above.
15. What is the SQL code for the following relational algebra
Select * from S2;
Select * from S2 where rating >8;
Select rating, * from S2;
Select rating, * from S2 where rating >8;
16. What is Data Warehouse?
A decision support database that is maintained separately from the organization’s operational database.
Support information processing by providing a solid platform of consolidated, historical data for analysis.
None of the above.
π
sname,rating( S 2 )
σ
rating>8( S 2 )
17. What is Data a Data Models ?
a collection of conceptual hardware for describing data, data relationships, data semantics, and consistency constraints.
a set of design objects for describing data, data relationships, data semantics, and consistency constraints.
a collection of conceptual tools for describing data, data relationships, data semantics, and consistency constraints.
None of the above.
18. What ‘s true about the Entity-Relationship Model (ER Model)?
perceives the real world as consisting of basic objects, called entities, and relationships among these objects.
was developed to facilitate database design by allowing specification of an enterprise schema, which represents the overall logical structure of a database.
is very useful because it can represent the meaning and relationship between objects of real world enterprise onto conceptual schema.
All of the above
19. What ‘s true Entity set ?
is a set of entities of the same type that share the same properties, or attributes.
An entity is a thing or object in the real world that is distinguishable from all other objects.
All of the above
None of the above 20. What ‘s a domain ?
A set of permitted values of an attribute.
A set of non permitted values of an attribute.
A set of permitted values of an table.
A set of permitted values of set of attributes.
21. An attribute is called simple attribute if :
if its value cannot be divided into subparts.
if its value can be divided into subparts.
None of the above
22. An attribute is called composite attribute if :
if its value cannot be divided into subparts.
if its value can be divided into subparts.
None of the above
23. An attribute is called Single-valued attribute if :
if it has only one value for a particular entity.
if it has many values for a particular entity.
if it has two or more values for a particular entity.
24. An attribute is called Multivalued attribute if :
if it has only one value for a particular entity.
if it has many values for a particular entity.
if it has more than one value for a particular entity.
25. Choose the wrong answer concerning the Degree of relationship ( The number of participating in a relationship).
A relationship of degree two is called binary relationship.
A relationship of degree three is called ternary relationship.
A relationship of degree four is called Quarternary relationship
A relationship of degree one is called unary relationship.
26. A One-to-one mapping is :
An entity in A is associated with at most one entity in B, and an entity in B is associated with at most one entity in A.
An entity in A is associated with any number (zero or more) of entities in B and an entity in B is associated with any number (zero or more) of entities in A.
An entity in A is associated with any number (zero or more) of entities in B. However, An entity in B can be associated with at most one entity in A.
27. The relational Model of Data is based on the concept of a
Relation.
Object
Both a and b
None of a and b
28. A Relation is a mathematical concept based on the ideas of
sets
Collections
Lists
vectors
29. The strength of the relational approach to data management comes from the formal foundation provided by the theory of objects.
True
false
30. Relation is a table of values that may be :
thought of as a set of rows.
though of as a set of columns.
though of as a set of string and Integers.
None of the above 31. In a relation:
Each row represents a fact that corresponds to a real-world entity or relationship.
Each row has a value of an item or set of items that uniquely identifies that row in the table.
Each row has a value of an item or set of items that not uniquely identifies that row in the table.
All of the above
32. CUSTOMER (Cust-id, Cust-name, Address, Phone#)
– CUSTOMER is a relation defined over the four attributes Cust-id, Cust-name, Address, Phone#.
– CUSTOMER is a table defined over the four attributes Cust-id, Cust-name, Address, Phone#.
– CUSTOMER is a table defined over the four fields Cust-id, Cust-name, Address, Phone#.
– All of the above.
– All of the above.
33. In a Relational Database:
Information are modeled by multiple relations interlinked explicitly by foreign keys.
Information are modeled by one relations interlinked explicitly by foreign keys.
Information are modeled by one relations interlinked explicitly by primery keys.
Information are modeled by multiple relations interlinked explicitly by primery keys.
34. A set S = {R1, R2, ..., Rn} of relation schemas that belong to the same database S
is the name of the database.
is the name of the schema.
is the name of the relation.
All of the above
35. The ER model describes data in a mini-world as:
Entities
relationships
attributes
values.
36. Link the of er-diagram symbol notation for er-schemas:
37. ER Model Concepts -Attributes
Attributes are properties used to describe a specific object or a set of objects (as we have learned, formally called an entity or a set of entities).
For example an EMPLOYEE is an object, it may have a Name, SSN, Address, Sex, BirthDate
Each attribute has a value set (or data type) associated with it – e.g. integer, string, subrange, enumerated type, …
A specific object (entity) will have a value for each of its attributes.
RELATIONSHIP TYPE
ENTITY TYPE
WEAK ENTITY TYPE
ATTRIBUTE
IDENTIFYING RELATIONSHIP TYPE
KEY ATTRIBUTE
MULTIVALUED ATTRIBUTE
DERIVED ATTRIBUTE
For example a specific employee may have Name='John Smith', SSN='123456789', Address ='731, Fondren, Houston, TX', Sex='M', BirthDate='09-JAN-55‘
Attributes can be used for relationship also!
