Relational Model in DBMS
Dr.E.F. Codd worked to improve the working of DBMSs to handle large volumes of data. He applied the rules of mathematics to solve the problems of earlier database models. Some important problems were as follows:
- Data Integrity
- Data Redundancy
In a relational model, data is stored in relations. Relation is another term used for table. A table in a database has a unique name that identifies its contents. Each table can be called an intersection of rows and columns. An important property of a table is that the rows are un-ordered. A row cannot be identified by its position in the table. Every table must have a column that uniquely identifies each row in the table. Relation, tuple, attributes, domain, degree, cardinality, relation instance and relation key are the terminology of relation database.
Database mcqs with answers set 8 includes the mcqs of relational database model, basics of relational database model, primary key, attributes, cardinality and candidate key. These database mcqs are very helpful for those who are preparing any computer related PPSC, SPSC, FPSC, KPPSC OR CSS based private or government jobs. Its also very helpful for international students who want to be appear in Oracle certification exams.
DBMS MCQs - Database MCQs With Answers Set 8
1. The columns of a table correspond to _____?A). Table
B). Record
C). Field
D). Cell
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2. The foreign key is found in _____ ?
A). Parent table
B). Dependent table
C). Pivot table
D). Index table
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3. A table must have _____ ?
A). Primary key
B). Secondary key
C). Composite key
D). Sort key
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4. A two-dimensional table of data is called a _____?
A). Group
B). Set
C). Declaration
D). Relation
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5. A table is perceived as two-dimensional structure composed of _____?
A). X and y co-ordinates
B). Matrix elements
C). Rows and columns
D). Intersection of data
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6. A relation is analogous to a _____?
A). File
B). Field
C). Record
D). Row
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7. A relation is also known as _____?
A). Table
B). Tuple
C). Relationship
D). Attribute
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8. An attribute is also known as a _____?
A). Table
B). Relation
C). Row
D). Field
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9. A row of a relation is called a (n) _____?
A). Attribute
B). Entity
C). Tuple
D). Both a and c
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10. A person, place, thing, event, or condition about which data is kept in the database is called _____?
A). Attribute
B). Field
C). Record
D). Entity
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A). Attribute
B). Data item
C). Record
D). Tuple
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12. Which of the following is NOT a general characteristic of relations _____?
A). Each row is unique
B). The order of columns is significant
C). The order of rows is insignificant
D). Columns are all elemental or atomic
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13. An index can be used to _____?
A). Improve the performance of the database
B). Document the structure of the database itself
C). Reduce data dependency for application programs
D). All
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14. Which of the following are properties of relations _____?
A). Each attribute has a unique name
B). No two rows in a relation are identical
C). There are no multivalued attributes in a relation
D). All of the above
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15. A key is _____?
A). A field that identifies only one record
B). The most important field in a record
C). The first field of table
D). None
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16. Which of the following describes the primary key _____?
A). It must be unique
B). It helps in indexing of a large database
C). It makes sorting quicker
D). All of the above
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17. Which of the following is NOT a good primary key _____?
A). Social security number
B). Order number
C). Zip code
D). Student ID number
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18. How many primary keys can a table have _____?
A). One
B). At least one, but not more than two
C). Between 1 and 5
D). No limit
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19. Which of the following should be a primary key _____?
A). A person's last name
B). An employee's salary
C). A customer's ID number
D). A salesperson's region
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20. Which field listed below is the most appropriate primary key _____?
A). A person's name
B). A person's street address
C). A person's birth date
D). A person's Social Security Number
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A). Secondary key
B). Index
C). Composite key
D). Linked key
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22. A candidate key is _____?
A). Primary key
B). The primary key selected to be the key of a relation
C). An attribute or group of attributes that can be the primary key
D). All
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23. An attribute in a relation of a database that serves as the primary key of another relation in the same database is called a _____?
A). Global key
B). Link key
C). Foreign key
D). None
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24. A primary key that consists of more than one attribute is called a _____?
A). Foreign key
B). Composite key
C). Multivalued key
D). Global key
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25. For each attribute of a relation, there is a set of permitted values, called the _____ of that attribute.
A). Domain
B). Set
C). Relation
D). Schema
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26. A domain is atomic if elements of the domain are considered to be _____ units.
A). Different
B). Constant
C). Indivisbile
D). Divisible
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27. Which one of the following is a set of one or more attributes taken collectively to uniquely identify a record?
A). Foreign key
B). Candidate key
C). Sub key
D). Super key
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28. The subset of a super key is a candidate key under what condition?
A). No proper subset is a super key
B). Subset is a super key
C). Each subset is a super key
D). All subsets are super keys
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29. An attribute in a relation is a foreign key if the _____ key from one relation is used as an attribute in that relation.
A). Candidate key
B). Primary key
C). Super key
D). None of these
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30. Course(course_id,sec_id,semester). Here the course_id, sec_id and semester are _____ and course is a _____?
A). Relations, Attribute
B). Attributes, Relation
C). Tuple, Attributes
D). Tuple, Relation
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