Important MCQ-Based Questions on Informatics Practices (IP) class 11 chapter-DBMS Concepts
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Find below Important MCQ-Based Questions on Informatics Practices (IP) class 11 chapter-DBMS Concepts
Important Questions for Informatics Practices (IP) class 11 chapter-DBMS Concepts set-1
Informatics Practices - MCQ on DBMS Concepts
Class XI
Q.1 Duplication of data is known as
a) data inconsistency.
b) data sharing.
c) data security.
d) data redundancy.
Answer:
(c)
Explanation: Data sharing is individual pieces of data shared among different users. Data security is protection of data against unauthorized access and data inconsistency means incorrect data.
Q.2 DBMS stands for
a) Database Management System.
b) Digital Based Mapping System.
c) Database Manipulation Software.
d) Database Mapping System.
Answer:
(a)
Explanation: DBMS is system software, which consists of interrelated databases and operations to manage databases.
Q.3 A set of attributes that can uniquely identify tuples within the relation
is known as
a) alternate key.
b) primary key.
c) secondary key.
d) candidate key.
Answer:
(b)
Explanation: Primary key is called so because it helps to distinguish one relation from another.
Q.4 Cardinality of relation represents
a) number of rows in a table.
b) number of columns in a table.
c) both rows and columns.
d) number of keys.
Answer:
(a)
Explanation: Cardinality refers to number of elements in a set. Number of elements represents the number of rows in a set.
Q.5 A logical unit of work that must succeed or fail in its entirety is known as
a) Termination.
b) TCP/IP.
c) Transaction.
d) TCP.
Answer:
(c)
Explanation: A database transaction comprises a unit of work performed within a database management system (or similar system) against a database, and treated in a coherent and reliable way independent of other transactions.
Q.5 A virtual table derived from one or more base tables is known as
a) parent table.
b) view.
c) child table.
d) base table.
Answer:
(b)
Explanation: The view is a kind of table, whose contents are taken upon other tables depending upon a given query condition. No stored file is created to store the contents of a view rather its definition is stored only.
Q.7 A language providing a set of operators for manipulating relations is called
a) relational algebra.
b) set difference.
c) natural join.
d) set intersection.
Answer:
(a)
Explanation: The relational algebra is a collection of operations on relations. Each operation takes one or more relations as its operands and produces another relation as its result.
Q.8 A system of rules that a DBMS uses to ensure that relationships between records in related tables are valid, and that users don’t accidentally delete or change related data is known as
a) referential secrecy.
b) referential intimacy.
c) referential upgradation.
d) referential integrity.
Answer:
(d)
Explanation: Referential integrity is a database concept that ensures relationships between tables remain consistent.
Q.9 The data model in which the data is represented by pointers is called
a) relational data model.
b) hierarchical data model.
c) network data model.
d) conceptual data model.
Answer:
(c)
Explanation: A network data model represents data by collection of records. Relationships among data are represented by links (pointers).
Q.10 The data model in which data is represented in the form of trees is called
a) relational data model.
b) hierarchical data model.
c) network data model.
d) database model.
Answer:
(b)
Explanation: A hierarchical data model represents data by records organized in form of trees and relationships among data are represented by links.
Q.11 The type of user, which does not work on database systems, is
a) physical storage system analyst.
b) end user.
c) application system analyst.
d) database analyst.
Answer:
(d)
Explanation: The other type of users apart from database analyst, are differentiated by the way they interact with the system. End user uses the database to retrieve some information. Physical storage system analyst is concerned with the physical implementation details of the database and application system analyst is concerned about the entire database at logical level.
Q.12 The ability to modify the scheme at physical level without affecting the scheme at conceptual level is known as
a) logical modification.
b) physical data independence.
c) physical modification.
d) logical data independence.
Answer:
(b)
Explanation: In physical data independence, the application programs remain the same even though the scheme at physical level gets modified. This is done in order to improve the performance of the system.
Q.13 The ability to modify the conceptual scheme without causing changes in the scheme at view level is known as
a) logical data independence.
b) view modification.
c) conceptual modification.
d) physical data independence.
Answer:
(a)
Explanation: The logical data independence ensures that the application program remains the same. Modifications at the conceptual level are necessary whenever a logical structure of the data gets altered.
Q.14 The size of database is usually measured in terms of
a) terabytes.
b) megabytes.
c) gigabytes.
d) databytes.
Answer:
(c)
Explanation: Gigabyte is a multiple of the unit byte for digital information storage. Since the giga prefix means 109, gigabyte means 1,000,000,000 bytes (10003, 109). Size of database is measured in gigabytes.
Q.15 The structure, which is a logical database structure, is
a) chain.
b) network.
c) circles.
d) square.
Answer:
(a)
Explanation: Structure in the form of chains is not allowed in database systems. Network, tree and relational data structure are the standard ways to represent the data in database systems.
Q.15 An organized collection of logically related data is known as
a) data.
b) database.
c) information.
d) metadata.
Ans. b)
Explanation: A database is a collection of interrelated data stored together to serve multiple applications.
Q.17 The level of database implementation, which is closest to users, is
a) view level.
b) physical level.
c) internal level.
d) user level.
Answer:
(a)
Explanation: View level is concerned with the way in which, the data is viewed by individual users. It is also known as external level.
Q.18 The abstract data type uses the concept of
a) data abstraction.
b) data integrity.
c) data redundancy.
d) data independence.
Answer:
(d)
Explanation: The abstract data type implement the concept of data independence in the sense that both hide the implementation details from the users.
Q.19 One of the disadvantages of database system is
a) shared data.
b) secured data.
c) performance overhead.
d) integrated data.
Answer:
(c)
Explanation: There are many disadvantages of database systems. For e.g., extra hardware requirement, complex system, performance overhead, etc.
Q.20 One of the advantages of database systems is
a) system complexity.
b) extra hardware requirement.
c) reduced data redundancy.
d) performance overhead.
Answer:
(c)
Explanation: Data redundancy means duplication of data. Database systems reduce redundancy of data.
Important Questions for Informatics Practices (IP) class 11 chapter-DBMS Concepts set-2
Q.21 The number of attributes in a relation is known as
a) degree.
b) rank.
c) key.
d) cardinality.
Answer:
(a)
Explanation: Relation consists of number of attributes and this number is known as degree.
Q.22 The database model in which data is represented in the form of table is
a) relational data model.
b) hierarchical data model.
c) internal data model.
d) external data model.
Answer:
(a)
Explanation: A relational data model is a model, which organizes the data into tables i.e. data is arranged in rows and columns.
Q.23 The process of data analysis used for grouping data is known as
a) cartesian product.
b) normalization.
c) projection.
d) cardinality.
Answer:
(b)
Explanation: Normalization is a basic concept used in analyzing data. This process in turn reduces the redundancy in the system.
Q.24 The command used in manipulating the database is known as
a) DML.
b) DDL.
c) DCL.
d) TCL.
Answer:
(a)
Explanation: DML stands for Data Manipulation Language. It provides commands to insert, delete and modify tuples in the database.
Q.25 The command used in creating and maintaining the database is
a) DML.
b) DDL.
c) DCL.
d) TCL.
Answer:
(b)
Explanation: DDL stands for data definition language. It provides statements for creating and deleting the database.
Q.26 The rule, which states the value of primary key can never be a null value, is
a) referential integrity.
b) entity integrity.
c) data integrity.
d) null integrity.
Answer:
(b)
Explanation: Primary key is a key, which uniquely identify, a specific instance of an entity. Therefore the value of primary key can never be null. The rule, which defines this fact, is known as entity integrity.
Q.27 The relation in which no two rows are identical and each table entry is single valued is
a) 1NF.
b) 2NF.
c) 3NF.
d) 5NF.
Answer:
(a)
Explanation: 1NF is used to remove the redundancy in the system. Therefore, there is no delicacy and repetition of values are not allowed.
Q.28 The relation in which each non-key attribute is functionally dependent on the entire key is
a) 1NF.
b) 2NF.
c) 3NF.
d) 5NF.
Answer:
(b)
Explanation: A table is said to be in 2NF, if it is in 1NF and all non-key attributes are totally dependent upon primary key.
Q.29 The relation in which each non-key attribute is no-transitively dependent on the entire key is
a) 1NF.
b) 2NF.
c) 3NF.
d) 4NF.
Answer:
(c)
Explanation: A table is said to be in 3NF, if it is in 2NF and transitively dependency is removed from the table.
Q.30 The function, which is used to combine related tuples from two relations, is
a) intersection.
b) difference.
c) join.
d) projection.
Answer:
(c)
Explanation: In the simplest form ,the join operation is just the cross product of the two relations. Two interrelated tuples from two different relations and are joined by this function.
Q.31 The command used to remove the table physically is
a) Alter.
b) Drop.
c) Delete.
d) Insert Into.
Answer:
(b)
Explanation: DROP TABLE table_name; is the command used to remove the table.
Q.32 The rule, which is used to specify the value in the certain column must satisfy a Boolean expression, is
a) foreign key constraint.
b) check constraint.
c) table constraint.
d) unique key constraint.
Answer:
(b)
Explanation: A check constraint is the most generic constraint type. The value in certain column should satisfy a truth-value expression. There is no limit to the number of check constraints that one can define on a column.
Q.33 The person responsible for the security and functioning of the database is
a) database administrator.
b) end user.
c) security officer.
d) programmer.
Answer:
(a)
Explanation: DBA is a person, who checks the authenticity of the database, whether database is secure and functioning properly.
Q.34 One of the disadvantages of the database system is that its
a) integrity is maintained.
b) high hardware configuration cost
c) reduced data redundancy.
d) increased durability.
Answer:
(b)
Explanation: Cost of hardware is one of the most important things for a database system. Its hardware configuration cost is high.
Q.35 The number of fundamental operations in relational algebra are
a) four.
b) five.
c) six.
d) seven.
Answer:
(c)
Explanation: There are six fundamental operations: select, project, rename, cartesian product, union and set-difference.
Q.35 The binary operation in relational algebra among the following is
a) select.
b) project.
c) rename.
d) union.
Answer:
(d)
Explanation: Union is the binary operation and others are unary operations.
Q.37 DDL stands for
a) Definition Data Language.
b) Data Definition Language.
c) Data Degree Language.
d) Database Degree Language.
Answer:
(b)
Explanation: A Data Definition Language (DDL) is a computer language for defining data structures.
Q.38 The number of data models available are
a) two.
b) three.
c) four.
d) five.
Answer:
(b)
Explanation: There are three data models available: relational, hierarchical and network data model.
Q.39 The advantage of hierarchical data model is
a) reduction of data dependency.
b) addition of node.
c) complexity.
d) machine performance.
Answer:
(b)
Explanation: The main advantage of the hierarchical data model is that, we can easily attach any child node to any parent node directly.
Q.40 The main disadvantage of hierarchical data model is
a) reduction of data dependency.
b) machine performance.
c) complexity.
d) flexibility.
Answer:
(a)
Explanation: The main disadvantage of this model is reduction of data dependency and if we delete parent node, child node will automatically get deleted.
Important Questions for Informatics Practices (IP) class 11 chapter-DBMS Concepts set-3
Q.41 The disadvantage of the relational model is
a) reduction of data dependency.
b) machine performance.
c) complexity.
d) flexibility.
Answer:
(b)
Explanation: The main disadvantage of relational model is machine performance. If the number of tables increases, the response time gets increased.
Q.42 A set of entities of some type constitutes an
a) entity group.
b) attributes.
c) entity set.
d) relationship.
Answer:
(c)
Explanation: A set of entities of some type, i.e., which share common properties constitutes an entity set.
Q.43 An association among several entities, is known as
a) entity group.
b) attributes.
c) entity set.
d) relationship.
Answer:
(d)
Explanation: A relationship is an association among several entities. For example, a teacher teaches a student. Here teacher and student are entities and teaches is the relationship between them.
Q.44 An attribute in a table, which is the key attribute in some other table, is known as
a) primary key.
b) composite key.
c) alternate key.
d) foreign key.
Answer:
(d)
Explanation: A foreign key is a field (or fields) that points to the primary key of another table. The purpose of the foreign key is to ensure referential integrity of the data.
Q.45 When multiple fields are used as a primary key, they are called a
a) primary key.
b) candidate key.
c) foreign key.
d) composite key.
Answer:
(b)
Explanation: Any key or minimum set of keys that could be a primary key is called a candidate key.
Q.45 Candidate keys which are not chosen as the primary key are known as
a) primary key.
b) composite key.
c) alternate key.
d) foreign key.
Answer:
(c)
Explanation: In the context of relational databases, an alternate key (or secondary key) is any candidate key which is not selected to be the primary key .
Q.47 The number of tuples in the relation is called its
a) degree.
b) cardinality.
c) attributes.
d) entity.
Answer:
(b)
Explanation: The term cardinality refers to the number of cardinal (basic) members in a set. Cardinality can be finite (a non-negative integer) or infinite.
Q.48 The rows of the table are called
a) attributes.
b) tuples.
c) cardinality.
d) entity.
Answer:
(b)
Explanation: In mathematics, a tuple is a sequence (or ordered list) of finite length. An n-tuple is a tuple with n elements.
Q.49 The columns of the table are called
a) attributes.
b) tuples.
c) cardinality.
d) entity.
Answer:
(a)
Explanation: A factor of an object or other kind of entity is known as attributes.
Q.50 The data stored at different levels should not affect each other when they get changed. It refers to
a) data integrity.
b) functional dependency.
c) referential integrity.
d) data independence.
Answer:
(d)
Explanation: Data independence is the type of data transparency that matters for a centralized DBMS. It refers to the immunity of user applications to make changes in the definition and organization of data, and vice-versa.
Q.51 The way a particular application views the data from the database is called
a) schema.
b) preschema.
c) post-schema.
d) subschema.
Answer:
(d)
Explanation: A subschema suggests a schema that is subordinate to some other schema.
Q.52 The smallest unit of database record is
a) tuple.
b) attribute.
c) field.
d) degree.
Answer:
(c)
Explanation: In computer science, data that has several parts can be divided into fields. For example, a computer may represent today's date as three distinct fields: the day, the month and the year.
Q.53 The disadvantage of file management system is
a) reduced redundancy.
b) no data sharing.
c) secured data.
d) standardized data.
Answer:
(b)
Explanation: In file management system, it is not possible to share the data. Due to non-sharing of data, redundancy of data is possible.
Q.54 The advantage of database management system is
a) reduced redundancy.
b) non-sharing of data.
c) inconsistency.
d) non-standardized data.
Answer:
(a)
Explanation: In database management system, it is possible to share the data. Due to sharing of data, redundancy of data is reduced.
Q.55 The logical data structure with one-to-many relationship, is
a) queue.
b) linked list.
c) tree.
d) stack.
Answer:
(c)
Explanation: In tree, one node (parent node) is connected to many other nodes (child nodes), thus a one-to-many relationship.
Q.55 The data model which is suitable for one-to-many relationship, is
a) relational.
b) network.
c) hierarchical.
d) conceptual.
Answer:
(c)
Explanation: Hierarchical data model is in the form of a tree. In tree, one node (parent node) is connected to many other nodes (child nodes), thus a one-to-many relationship.
Q.57 When both the relations are of the same degree and the domain of the attributes of both the relation is same, it is known as
a) intersection compatibility.
b) projection compatibility.
c) union compatibility.
d) selection compatibility.
Answer:
(c)
Explanation: The union compatibility is defined as such:
(1 the two relations have the same degree n (number of attributes) , and (2 domain (Ai)= domain (Bi) for 1=<i<=n, where domain stands for data type.
Q.58 A tuple is equivalent to
a) relation.
b) record.
c) degree.
d) operator.
Answer:
(b)
Explanation: The rows of the table are called tuples, which are equivalent to a record.
Q.59 The database model which is represented in the form of tables is
a) relational data model.
b) network data model.
c) hierarchical data model.
d) tree data model.
Answer:
(a)
Explanation: The relational model for database management is a database model based on first-order predicate logic, first formulated and proposed in 1969 by E.F. Codd. The relational data model uses the concept of tables.
Q.60 Data items grouped together for storage purposes is called a
a) table.
b) relation.
c) record.
d) tree.
Answer:
(c)
Explanation: An ordered set of fields, usually stored contiguously is known as a record.
Q.61 Data redundancy is
a) collection of relevant data.
b) duplication of data.
c) storage of data in a database.
d) security of data.
Answer:
(b)
Explanation: Data redundancy sometime refers to in computer data storage, is a property of some disk array which provides fault tolerance, so that all or part of the data stored in the array can be recovered in the case of disk failure.
Q.62 Data inconsistency
a) may exist because of data redundancy.
b) can be eliminated by data redundancy.
c) helps maintain the database.
d) is a requirement of a good database.
Answer:
(a)
Explanation: Data inconsistency exists when different and conflicting version of same data appear in different places.
Q.63 Database abstraction is
a) the detailed database structure.
b) a vague database structure.
c) hiding of complicated details from the user.
d) laid down by Mr. E.F.Codd.
Answer:
(c)
Explanation: Abstraction is the process of taking away or removing characteristics from something in order to reduce it to a set of essential characteristics.
Q.64 The three levels of abstraction are
a) Internal, Physical and External.
b) Internal, Conceptual and Logical.
c) Internal, Conceptual and External.
d) Internal, Conceptual and Physical.
Answer:
(c)
Explanation: Abstraction is the process of taking away or removing characteristics from something in order to reduce it to a set of essential characteristics. The three levels o abstraction are internal, conceptual and external.
Q.65 Abstraction at the Physical level
a) provides views according to user’s requirements.
b) describes how data are actually stored.
c) describes the relationships among the data.
d) is closest to the user.
Answer:
(b)
Explanation: The lowest level of abstraction describes how a system actually stores data. The physical level describes complex low-level data structures in detail.
Q.65 Abstraction at the Conceptual level
a) provides views according to user’s requirements.
b) describes how data are actually stored.
c) describes the relationships among the data.
d) is closest to the user.
Answer:
(c)
Explanation: This level of abstraction describes what data the database stores, and what relationships exist among those data.
Q.67 Abstraction at the External level
a) provides views according to user’s requirements.
b) describes how data are actually stored.
c) describes the relationships among the data.
d) is closest to the user.
Answer:
(a)
Explanation: The highest level of abstraction describes only part of the entire database.
Q.68 Data independence
a) refers to storage of data separately from information.
b) refers to updation of all tables independently.
c) keeps the data accurate and consistent.
d) allows changes in structure without affecting access of data.
Answer:
(d)
Explanation: Data independence is the type of data transparency that matters for a centralized DBMS. It refers to the immunity of user applications to make changes in the definition and organization of data, and vice-versa.
Q.69 The three main data models are
a) Object-Oriented, Network and Hierarchical.
b) Relational, Network and Hierarchical.
c) Relational, Object-based and Hierarchical.
d) Object-based, Relational and Network.
Answer:
(b)
Explanation: A data model is an abstract model that describes how data is represented and accessed. Data models formally define data elements and relationships among data elements for a domain of interest. The main data models are: relational, network and hierarchical.
Q.70 Rows in a relation are also called
a) tuple.
b) column.
c) relation.
d) attribute.
Answer:
(a)
Explanation: Tuples are typically used to represent a row in a database table or a proposition.
Q.71 A table is also called
a) tuple.
b) column.
c) relation.
d) attribute.
Answer:
(c)
Explanation: A relation is usually described as a table, which is organized into rows and columns.
Q.72 A column is called
a) tuple.
b) column.
c) relation.
d) attribute.
Answer:
(d)
Explanation: An attribute is a factor of an object or other kind of entity. In tables, each column represents an attribute.
Q.73 Domain is
a) the set of values existing in a column.
b) the set of names of the relations.
c) the set of possible values in a column.
d) the product of number of rows and columns.
Answer:
(c)
Explanation: Domain is the set of values of the independent variable for which a function is defined.
Q.74 Degree is
a) number of columns in a table.
b) number of rows in a table.
c) the product of number of rows and columns.
d) the same for every table.
Answer:
(a)
Explanation: In relational model, degree refers to the number of columns in a table.
Q.75 Cardinality is
a) number of columns in a table.
b) number of rows in a table.
c) an unknown quantity for a table.
d) the same for every table.
Answer:
(b)
Explanation: In set theory, cardinality refers to the number of members in the set. When specifically applied to database theory, the cardinality of a table refers to the number of rows (or tuples) contained in a table.
Q.76 Primary Key
a) is the first column of a relation.
b) stores NULL for unknown values.
c) can have only unique values.
d) can hold only numeric values.
Answer:
(c)
Explanation: The primary key of a relational table uniquely identifies each record in the table.
Q.77 Foreign Key
a) is a column of another relation in the database.
b) verifies values against the primary key in another relation.
c) can have only unique and non-null values.
d) specifies the possible values a column can have.
Answer:
(b)
Explanation: Foreign key is a referential constraint between two tables. The foreign key identifies a column or a set of columns in one (referencing) table that refers to a column or set of columns in another (referenced) table.
Q.78 Alternate Keys are
a) candidate keys that are not part of the primary key.
b) candidate keys that can be used as foreign keys.
c) foreign Keys that can also be used as primary keys.
d) candidate keys, including primary key.
Answer:
(a)
Explanation: An alternate key (or secondary key) is any candidate key which is not selected to be the primary key (PK).
Q.79 Candidate Keys
a) cannot be part of the primary key.
b) are the foreign key and primary key attributes.
c) uniquely identifies rows in a table.
d) uniquely identifies columns in a table.
Answer:
(c)
Explanation: A candidate key is a combination of attributes that can be uniquely used to identify a database record without any extraneous data. Each table may have one or more candidate keys. One of these candidate keys is selected as the table primary key.
Q.80 The select operation selects
a) conditions to be satisfied.
b) columns that satisfy a condition.
c) rows that satisfy a condition.
d) relation that satisfy a condition.
Answer:
(c)
Explanation: The select operation selects tuples from a table that satisfy a given predicate.
Q.81 The project operation selects
a) selects conditions to be satisfied.
b) selects columns that satisfy a condition.
c) selects rows that satisfy a condition.
d) selects relation that satisfy a condition.
Answer:
(b)
Explanation: The project operation yields a “vertical” subset of a given relation.
Q.82 The Cartesian product
a) is a product of two relations.
b) has as many rows as the sum of the 2 relations.
c) has as many columns as the larger table.
d) has rows that are common in participating tables.
Answer:
(a)
Explanation: The Cartesian product is a binary operation and is denoted by a cross. It yields a relation with all possible combinations of the tuples of the two relations operated upon.
Q.83 The Union operation produces a relation with
a) double the number of tuples.
b) tuples existing in any one relation.
c) tuples of both the relations.
d) tuples common to both relations.
Answer:
(d)
Explanation: The union operation is a binary operation that requires two relations as its operands. It produces a third relation that contains tuples from both the operand relations.
Q.84 A relation can have
a) one primary key.
b) two primary keys.
c) three primary keys.
d) four primary keys.
Answer:
(a)
Explanation: The primary key of a relational table uniquely identifies each record in the table. A relation has one primary key.
Q.85 In hierarchical model, the number of parent record(s) is/are
a) one.
b) two.
c) three.
d) many.
Answer:
(a)
Explanation: The hierarchical model structures data as a tree of records, with each record having one parent record and many children.
Q.85 In network model, the number of parent record(s) is/are
a) one.
b) two.
c) three.
d) many.
Answer:
(d)
Explanation: The network model allows each record to have multiple parent and child records, forming a lattice structure.
Q.87 The original inventor of network model is
a) Charles Bachman.
b) Charles Goodman.
c) Charles Johnson.
d) Charles Gilson.
Answer:
(a)
Explanation: The network model is a database model conceived as a flexible way of representing objects and their relationships. Its original inventor was Charles Bachman, and it was developed into a standard specification published in 1969 by the CODASYL Consortium.
Q.88 The number of tuples present in a table at any instance is known as
a) intension.
b) extension.
c) gradation.
d) instantiation.
Answer:
(b)
Explanation: 'Extension' to refer to particular instances of a database. This is time dependent.
Q.89 A constant value that gives the name, structure of table and the constraints laid on it is known as
a) intension.
b) extension.
c) gradation.
d) instantiation.
Answer:
(a)
Explanation: 'Intension' refers to the schema of a database.
Q.90 The integrity rules are
a) Entity and Referential Integrity.
b) Null and Full Integrity.
c) Syntax and Semantic Integrity.
d) Primary and Foreign Integrity.
Answer:
(a)
Explanation: Entity Integrity states that primary key cannot have NULL value. Referential Integrity states that foreign Key can be either a NULL value or should be primary key value of other relation.
Q.91 A NULL value is
a) equal to zero (0.
b) same as blank spaces.
c) an unknown value.
d) same as special characters.
Answer:
(c)
Explanation: A NULL value is a special value in computer programming. It means zero value.
Q.92 After project operation,
a) duplicate rows are automatically removed.
b) columns appear in the same order as in the table.
c) rows satisfying a condition are displayed.
d) conditions are specified.
Answer:
(a)
Explanation: The project operation yields a “vertical” subset of a given relation. Duplicate values are deleted after this operation.
Q.93 The ability of the system to distinguish between two different objects that have the same identity is known as
a) encapsulation.
b) complex state.
c) type extensibility.
d) object identity.
Answer:
(d)
Explanation: An identity in object-oriented programming, object-oriented design and object-oriented analysis describes the property of objects that distinguishes them from other objects.
Q.94 In relational data model,
a) records are organized as trees.
b) records are connected by links.
c) data is organized into tables.
d) data security cannot be ensured.
Answer:
(c)
Explanation: Relation is a two-dimensional table. In relational model, data is organized in the form of tables.
Q.95 In network data model,
a) records are organized as trees.
b) records are connected by links.
c) data is organized into tables.
d) data modification cannot be performed.
Answer:
(b)
Explanation: The core purpose of a network data model is to provide an accurate representation of a network as a set of links and nodes.
Q.95 In hierarchical data model,
a) records are organized as trees.
b) records are connected by links.
c) data is organized into tables.
d) data security cannot be ensured.
Answer:
(a)
Explanation: A hierarchical data model is a data model in which the data is organized into a tree-like structure.
Q.97 The ability to define data types using primitive types using which complex objects can be built is known as
a) object identity.
b) complex state.
c) simple state.
d) type extensibility.
Answer:
(b)
Explanation: It refers to ability of building of complex data types. This is done by defining data types using primitive types.
Q.98 ACID properties refers to
a) Atomicity, consistency, isolation and durability.
b) Atomicity, consistency, isolation and direction.
c) Atomicity, controllability, isolation and durability.
d) Acidity, consistency, isolation and durability.
Answer:
(a)
Explanation: ACID properties are an important concept for databases. The acronym stands for Atomicity, Consistency, Isolation, and Durability. The ACID properties of a DBMS allow safe sharing of data.
Q.99 Collection of data sent as a single message is known as
a) database.
b) datagram.
c) data control.
d) data transfer.
Answer:
(b)
Explanation: Datagram is a self-contained, independent entity of data carrying sufficient information to be routed from the source to the destination computer without reliance on earlier exchanges between this source and destination computer and the transporting network.
Q.100 The data model, which is used for database management, is
a) table data model.
b) internetwork data model.
c) tree data model.
d) hierarchical data model.
Answer:
(d)
Explanation: Data is organized into a tree like structure in hierarchical model.