Question # 1

Select the correct statement among the following on proper naming of schema constructs:

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Entity type name applies to all the entities belonging to that entity type and therefore a plural name is selected for entity type.

In the narrative description of the database requirements, verbs tend to indicate the names of relationship types.

The nouns arising from a database requirement description can be considered as names of attributes.

Additional nouns which are appearing in the narrative description of the database requirements represent the weak entity type names.

Which of the following constraints enforces referential integrity?

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FOREIGN KEY

CHECK

PRIMARY KEY

UNIQUE

Select the correct statement among the following.

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Role names are not technically necessary in relationship types when all the participating entity types are distinct

When different entity types participate only once in a single relationship type it is called a recursive relationship.

Cardinality ratios for binary relationship are displayed on Entity Relationship Diagrams by using a diamond shape notation.

Partial participation which is also called existence dependency is displayed as a double line connecting the participating entity type to the relationship.

Which of the following is INCORRECT statement concerning the database design process?

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During requirements collection and analysis phase, one can gather the data requirements of database users.

By referring to a high level data model, it is possible to understand the data requirements of the users, entity types, relationships and constraints.

Transformation of the high level data model into the implementation data model is called logical design or data model mapping

During the logical design phase of internal storage structures, access paths and file organization for the database files are specified.

Which of the following is true about NOT NULL constraint?

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enforce domain integrity

limit the values that can be placed in a column

prevents any actions that would destroy links between tables with the corresponding data values

enforces the uniqueness of the values in a set of columns

The ____ constraint specifies whether each entity supertype occurrence must also be a member of at least one subtype

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specialization

uniqueness

inheritance

completeness

Which of the following is disadvantage of chaining technique to handle the collisions?

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Unlimited Number of elements

Fast re-hashing

Overhead of multiple linked lists

Maximum number of elements must be known

If W, X, Y and Z are attributes of a relation, which of the following inference rules for functional dependencies is correct?

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If (X, Z) -> Y then X -> Y and Z -> Y.

If X -> Y and X -> Z then X -> (Y, Z)

If XY then Y -> X

If X -> Y then (X, Z) -> (Y,W).

Which of the following functions are NOT performed by a database administrator?

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Planning, designing and implementing database systems

Establishing standards and procedures for database systems

Communicating with database users

Allocation of storage locations and data structures

Identify the correct statement.

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Referential integrity constraints check whether the primary key values are unique

Referential integrity constraints check whether an attribute value lies in the given range

Referential integrity constraints are specified between entities having recursive relationships

When Referential integrity rules are enforced, a tuple in one relation that refers to another relation must refer to an existing tuple.

Only one type of constraint can be enforced in any table by CREATE command

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True

False

Not Sure

Select 'NORTH', CUSTOMER From CUST_DTLS Where REGION = 'N' Order By CUSTOMER Union Select 'EAST', CUSTOMER From CUST_DTLS Where REGION = 'E' Order By CUSTOMER The above statement

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Has an error - the string should be in double quotes

Has an error - ORDER BY clause.

Does not have an error.

Has an error - the string in single quotes 'NORTH' and 'SOUTH'.

Which of the following is true for the relational model?

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Degree of a relation is the number of rows in a relation

Null value is a blank or zero value given to an attribute value when its value is inapplicable or its value is unknown

Complex key is a key consisting of more than one attribute.

Constraint is a rule that restricts the values in a database.

Which of the following is not true with respect to denormalization ?

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A denormalized data model is not the same as a data model that has not been normalized

Denormalization takes place before the normalization process

It is an attempt to optimize the performance of database

Denormalization process can not be initiated before the Database design

Which of the following is used to add or drop columns in an existing table?

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ALTER

HAVING

SELECT

THEN

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