CBSE Class 12 Informatics Practices Database Fundamentals MySQL Revision Tour Worksheet

CBSE Class 12 Informatics Practices Database Fundamentals Mysql Revision Tour. Students can download these worksheets and practice them. This will help them to get better marks in examinations. Also refer to other worksheets for the same chapter and other subjects too. Use them for better understanding of the subjects.

UNIT 3

CHAPTER 13: DATABASE FUNDAMENTALS - MYSQL REVISION TOUR

Database: Collection of logically related data stored in a structure format.

DBMS: Software used to manage databases is called Data Base Management System (DBMS).

RDBMS: A DBMS used to manage Relational Databases is called an RDBMS (Relational Data

Base Management System). Some popular RDBMS software available are: Oracle, MySQL,

Sybase, and Ingress.

Benefits of using a DBMS are:

a. Redundancy can be controlled b. Inconsistency can be avoided

c. Data can be shared d. Security restrictions can be applied.

MySQL: It is an Open Source RDBMS Software. It is available free of cost.

Relation/Table: A table refers to a two dimensional representation of data arranged in columns

(also called fields or attributes) and rows (also called records or tuples).

Key: A column or a combination of columns which have some specific characteristics in a relation

e.g. are Primary Key, Candidate Key and Foreign Key etc.

Primary Key: The group of one or more attribute(s) used to uniquely identify each row/tuple of a

relation/table is called its Primary Key.

Candidate Key: A group of columns which can be set as the primary key of a relation is called a

candidate key because it is one of the candidates available to be the primary key of the relation.

Alternate Key: A candidate key of a table which is not set as primary key is called its Alternate Key.

Degree is the number of columns/attributes in the table.

Cardinality is the number of rows/tuples in a table.

SQL (Structured Query Language): It is the language used to manipulate and manage databases

and tables within them using an RDBMS. There are following four types of SQL commands:

1. DDL (Data Definition Language): Deals with the Structure (create, remove, or modify) of

databases and tables e.g. CREATE, DROP, ALTER.

2. DML (Data Manipulation Language): Used to manipulate data/ values within tables e.g.

INSERT, UPDATE, DELETE.

3. DCL (Data Control Language): Used to control the access to the databases and tables e.g.

GRANT, REVOKE.

4. TCL(Transaction Control Language): used to manage and control the transaction e.g.

COMMIT , ROLLBACK, SAVEPOINT

Some Commonly used DDL Command are as follows:-

SNo Command, Syntax and Purpose

1 Command : Create Database

Syntax: Create database ;

Purpose: Creates a database with specified name

2 Command : Create Table

Syntax: Create Table

( , Data Type1,, Data Type2);

Purpose: Creates a table with specified name

3 Command : Alter Table

Syntax: Alter Table

Purpose: Show structure of table

11 Command : Update

Syntax: : Update

Set =Value

Where ;

Purpose: Update or Modify the data in tables

Following are the clauses which can be used with select command

SNo CLAUSE EXPLANATION

1 DISTINCT Used to display distinct values from a column of a table

2 WHERE Used to specify the condition based on which rows of a table are dispalyed

3 BETWEEN Used to define the range of values within which the column values must fall to

make a condition true. It include both upper and lower values.

4 IN Used to select values that natch any values in a lsit of specified values

5 LIKE Used for pattern matching of string data using wildcard characters % and _

6 IS NULL/ NOT Used to select rows in which the specified column is NULL (or is NOT NULL)

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