Basic Concept of Database
Category : 10th Class
Basic Concept of Database
DBMS (Database Management System) is a program which retrieves, modifies and stores the data in database on request. A complete DBMS includes software and hardware utilities, procedures, data and users. The following are the different types of users who can retrieve or access the data from database.
End User
It is a person who interacts directly with the DBMS through client software.
DBA (Database Administrator)
It is a person responsible for implementing the database management system within an organization.
Application Programmer
It is a person who develops the applications that is used for interacting with the, data. The RDBMS (Relational Database Management System) is the advanced form of DBMS. In RDBMS data is stored in the form of table. Each table has unique name. A table contains one or more rows and columns. The total number of attributes or columns which compromise a table is called the degree of the table. RDBMS creates; relationship between two or more tables. The following are some of the key terms in RDBMS:
Tuple
It represents an object and information about the object. It contains the datal corresponding to an entity. The number of tuples in a relation is called the cardinality of the relation.
Table
It is a collection of rows and columns that contains data. A column contains same type of data, such as class name, table does not contain marks.
Attribute
It is the property of an entity that differentiates it from other entities and provides information about the entity.
Domain
It describes the set of possible values for a given attribute. Any value that appears under a column must belongs to its domain. While designing the tables of a database, you need to enforce the data integrity in the database. Enforcing the data integrity ensures that data in the database is valid and correct. You enforce the data integrity in a database by using the following types of keys:
Candidate Key
It is an attribute that contains unique value. The candidate key has the maximum eligibility to make primary key.
Unique Key
It is an attribute that contains unique value. Unique key can contain NULL value.
Primary Key
It is an attribute that contains unique value. The main difference between primary Key and unique key is that primary key cannot contain a NULL value.
Foreign Key
it creates relationship between two or more table. Basically it is an attribute that appears as a candidate key in one table and primary key in another table.
An organized collection of data is called database. Which of the following is/are the advantage of database?
(A) Data sharing
(B) Avoiding data redundancy
(C) Securing data
(D) All of these
(E) None of these
Answer: (d)
Explanations
Correct Option:
(D) Database provides data sharing, avoiding data redundancy, avoiding inconsistency of data and securing data.
Incorrect Options:
Therefore, option (D) is correct and rest of the options is incorrect.
Which one of the following is responsible for implementing the database management system within an organization?
(A) End User
(B) DBA
(C) Application Programmer
(D) All of these
(E) None of these
Answer: (b)
Explanations
Correct Option:
(B) DBA is a person responsible for implementing the database management system within an organization.
Incorrect Options:
Therefore, option (D) is correct and rest of the options is incorrect.
Joseph develops a table. In this table he wants to use a constraint that does not allow null value. Which one of the following keys he needs to apply?
(A) Candidate key
(B) Unique key
(C) Primary Key
(D) All of these
(E) None of these
Answer: (C)
Explanation
Correct Option:
(C) It is an attribute that contains unique value. The main difference between primary key and unique key is that primary key cannot contain a NULL value.
Incorrect Options:
Therefore, option (C) is correct and rest-of the options is incorrect
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