Relational Database Class 11

Relational Database Class 11
Notes

chapter-16

Relational Database Class 11
Relational Database Class 11

Introduction :

Relational Database Class 11

A database system is basically a computer based record keeping system. The collection of data, usually referred to as the database, contains information about one particular enterprise. It maintain any information that may be necessary to the decision-making process involved in the management of that organization. A database may also be defined as a collection of interrelated data stored together to serve multiple application; the data is such stored so that it is independent of programs which use data.

Database:-

A database may be defined as a collection of interrelated data stored together to serve multiple applications.

Purpose of DBMS

A database should be a repository of the data needed for an organization’s data processing. That data should be accurate, private, and protected from damage. It should be organized so that diverse applications with different data requirements can employ the data.

DBMS:-

A DBMS (Data Base Management System) refers to a software that is responsible for storing, maintaining and utilizing databases. A database along with a DBMS is referred to as a database system.

DATA REDUNDANCY:-

Duplication of data is known as Data Redundancy.

Relational Database Model

In relational data model, the data is organized into tables(i.e., rows and columns). These tables are called relations. A row in a table represents a relationship among a set of values. Since a table is a collection of such relationships, it is generally referred to using the mathematical term relation, from which the relational data model derives its name.

Let us see how a sample database can be represented in relational form. The sample database being shown here has three tables (relations) : Suppliers, Items, Shipments.

SuppNoSupp_NameStatusCity
S1Britannia10Delhi
S2New Bakers30Mumbai
S3Mother Dairy10Delhi
S4Cookz50Bangalore
S5Haldiram40Jaipur
Suppliers – Relational Database Class 11
Item_NoItem_NamePrice
11Milk15.00
12Cake5.00
13Bread9.00
14Milk Bread14.00
15Plain Biscuit6.00
16Cream Biscuit10.00
17Ice Cream16.00
18Cold Drink8.00
19Namkeen15.00
Items – Relational Database Class 11
SuppNoItemNoQty_supplied
S11210
S11320
S11620
S21420
S21510
S31110
S31710
S41830
S51930
Shipments – Relational Database Class 11

Notice, that here each supplier has a unique supplier number, exactly one name, status value and location. Likewise, we assume that each item has a unique item number, name, price; and also that, at any given time, no more than one shipment exists for a given supplier/item combination.

Relational Database Class 11

Components of a Table:-

Byte:-

a byte is a group of eight bits and is used to store a character.

Data Item(Field):-

a data item is smallest unit of named data. it may consist of any number of bits or bytes.

Record:-

a record is named collection of data items which represents a complete unit of information.

Table:-

a table is a named collection of all occurrences of a given type of logical record.

Relational Databases class11 notes

The Relation Model Terminology:-

The relational model was propounded by E.F. Codd of the IBM and has since been acknowledged as a very important concept in DBMS (Data Base Management Systems) technology.

Relation:-

in general, a relation is a table i.e., data arranged in rows and columns.

Domain:-

A domain is a pool of values from which the actual values appearing in a given column are drawn.

Tuples:-

The rows of a relation is known as tuples.

Attributes:-

The columns of a relation is known as Attributes.

Degree:-

The number of attributes in a relation is called Degree.

Cardinality:-

The number of rows in a relation is known as Cardinality.

view type:-

A view is a (virtual) table that does not really exist in its own right but is instead derived from one or more underlying base table(s).

Keys:-

It is important to be able to specify how rows in a relation are distinguished conceptually, rows are distinct from one another,

but from a database perspective the difference among them must be expressed in terms of their attributes. Keys come here for a rescue.

Primary Key:-

a primary key is set of one or more attributes that can uniquely identify tuples within the relation.

Candidate Key:-

All attribute combinations inside a relation that can serve as primary key are candidate keys as they are candidates for the primary key position.

Alternate key:-

a candidate key that is not the primary key is called an alternate key.

Foreign key:-

a non-key attribute, whose values are derived from the primary key of some other table, is known as foreign key in its current table.

Referential Integrity:-

Referential Integrity is 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.

MySQL Database System

The key role of a database management system is information management. A database server is the key to solving the problems of information management. In general, a server must reliably manage a large amount of data in multi-user environment so that many users can concurrently access the same data.

Some of the key features of MySQL are :

  1. Speed
  2. Ease of use
  3. Cost. MySQL is free of cost.
  4. Query Language Support
  5. Portability
  6. Data Types
  7. Security
  8. Scalability and Limits
  9. Connectivity
  10. Localization
  11. Client and Tools

MySQL and SQL

SQL is a query language, whereas MySQL is a relational database that uses SQL to query a database. You can use SQL to access, update, and manipulate the data stored in a database. However, MySQL is a database that stores the existing data in a database in an organized manner.

Processing Capabilities of SQL

The SQL has proved to be a language that can be used by both casual users as well as skilled Programmer. It offers a variety of processing capabilities, simpler ones of which maybe used by the former and the more complex by the latter class of users. The various processing capabilities of SQL are :

  1. Data Definition Language (DDL)
  2. Interactive data Manipulation Language (DML)
  3. Embedded Data Manipulation Language
  4. View Definition
  5. Authorization
  6. Integrity
  7. Transaction Control

String datatypes:-

CHAR, VARCHAR, VARCHAR2

Numeric datatype:-

NUMBER, NUMERIC, INT, FLOAT, DECIMAL

Data Dictionary:-

a data dictionary is a file that contains “metadata” i.e., “data about data”.

Classification of SQL Statements

SQL provides many different types of commands used for different puposes. SQL commands canbe divided into following categories :

1. DDL:-

Data Definition Language (DDL) OR Data Description Language (DDL).

2. DML:-

Data Manipulation Language (DML).

3. TCL:-

the TCL commands are used to manage transactions.

4. Session Control Commands

DDL Commands

The Data Definition Language (DDL) commands, as the name suggests, allow you to perform task related to data definition. That is, through these commands, you can perform tasks like :

(i) Create, alter, and drop schema objects

(ii) Grant and revoke privileges and roles

(iii) Maintenance commands

DML Commands

By data manipulation, we mean :

  • the retrieval of information stored in the database.
  • the insertion of new information into database.
  • the deletion of information from the database.
  • the modification of data stored in the database.

The DMLs are basically of two types :

(i) Procedural DMLs require a user to specify what data is

needed and how to get it.

(ii) Non-procedural DMLs require a user to specify what data isneeded without specifying how to get it.

TCL Commands

Examples of TCL commands:

  • COMMIT– commits a Transaction.
  • ROLLBACK– rollbacks a transaction in case of any error occurs.
  • SAVEPOINT–sets a savepoint within a transaction.
  • SET TRANSACTION–specify characteristics for the transaction.

Relational Database Class 11 important questions

Relational Database Class 11 notes more details

Python Tutorial 2021

FAQ :-

Q 1. What is Relational Database with example?

Ans. Popular examples of standard relational databases include Microsoft SQL ServerOracle DatabaseMySQL and IBM DB2. Cloud-based relational databases, or database as a service (DBaaS), are also widely used because they enable companies to outsource database maintenance, patching and infrastructure support requirements.

Q 2. Which are relational databases?

Ans. A relational database is a type of database that stores and provides access to data points that are related to one another. … The columns of the table hold attributes of the data, and each record usually has a value for each attribute, making it easy to establish the relationships among data points.

Q 3. What is relational database system?

Ans. A relational database management system (RDBMS or just RDB) is a common type of database that stores data in tables, so it can be used in relation to other stored datasets. … The data is often stored in many tables, also called ‘relations’. These tables are divided into rows, also called records and columns (fields).

Q 4. What is Relational Database Class 11 class 11?

Ans. INFORMATICS PRACTICES – CLASS XI. A database management system (DBMS) or database system in short, is a software that can be used to create and manage databases. DBMS lets users to create a database, store, manage, update/modify and retrieve data from that database by users or application program

What is a relational database management system?

A database system is basically a computer based record keeping system. The collection of data, usually referred to as the database, contains information about one particular enterprise. It maintain any information that may be necessary to the decision-making process involved in the management of that organization. A database may also be defined as a collection of interrelated data stored together to serve multiple application; the data is such stored so that it is independent of programs which use data.

What is relational database management system PDF?

RDBMS The database system in which the relationships among different tables are maintained is called Relational Database Management System. Both RDBMS and DBMS are used to store information in physical database.  RDBMS solution is required when large amounts of data are to be stored as well as maintained.

What are the distinct features of relational database management system?

Features of RDBMS Systems:

All data stored in the tables are provided by an RDBMS. Ensures that all data stored are in the form of rows and columns. Facilitates primary key, which helps in unique identification of the rows. Index creation for retrieving data at a higher speed.

What are the 4 types of DBMS?

Four types of database management systems
hierarchical database systems.
network database systems.
object-oriented database systems.

What are the 5 types of databases?

Types of databases
Centralised database.
Distributed database.
Personal database.
End-user database.
Commercial database.
NoSQL database.
Operational database.
Relational database.

Relational Database Class 11

Relational Database Class 11