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CLASS XII
INFORMATICS PRACTICES(065)
Ch 5: MySQL REVISION TOUR
INTRODUCTION:
Database is a structured, organised collection or set of data held in a computer and a database
system is a computer based record keeping system
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▪ Reduced updates on Errors and Increase Consistency
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▪ Improved Data Sharing and better-managed data allow business to make quality business
decisions which will promote the growth of the organization
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▪ it provides a strong framework for Data backup
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The relational data model organized the ata into tables known as relation and maintain a
relationship with other values
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• Relation: Relation (collection of rows and columns) on which we can perform various
operations
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• Field: Set of characters that represents specific data element
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A record can have fields of different data
types
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• Table: Collection of rows and columns that contains useful data/information is called a
table
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It is also known as record
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It is also termed as field or data
item
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• Cardinality: Number of tuples in a relation is called cardinality of a relation
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This key can never be duplicated and NULL
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This key is used to enforce referential integrity
in RDBMS
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• Alternate Key: All the candidate keys other than the primary key of a relation are
alternate keys for a relation
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Example: Relation: Student
AdNo
Name
Class Section
Average
101
Anu
12
A
85
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7
203
Leena
11
B
95
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32
305
Surpreeth
9
C
70
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0
Fields (Attributes/Columns):- AdNo, Name, Class, Section and Average
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Cardinality: 6 (Number of rows)
Primary key : AdNo
Alternate key: Name

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Referential Integrity:
 A referential integrity constraint is specified between two tables
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In other words, any foreign key field must agree
with the primary key that is referenced by the foreign key
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 In the Referential integrity constraints, if a foreign key in Table 1 refers to the Primary
Key of Table 2, then every value of the Foreign Key in Table 1 must be null or be
available in Table 2
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mysql
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Provides features that support secure environment for storing, maintaining and accessing
data
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 Create and supported by MySQL AB, a company based in Sweden
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On April 2009 Oracle Corp
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 The chief inventor of MySQL was Michael Widenius(a
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a Monty)
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The logo of MySQL is dolphin and name of that
dolphin is ‘Sakila’
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 It operates using Client/Server architecture in which the server runs on the machine
containing the database and client connects to server over a network
 MySQL is a multiuser database system, meaning several users can access the database
simultaneously
MySQL and SQL(Structured Query Language) :
SQL is a non procedural language that is used to create, manipulate and process the
databases(relations)
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MySQL is a popular Relational Database Management System(RDBMS) , freely available and
open source that uses SQL
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mysql
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Classification of SQL Statements:
1
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e
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2
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e
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3
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The commonly used commands in TCL are COMMIT, ROLLBACK, and
SAVEPOINT
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Data types of SQL: Just like any other programming language, the facility of defining data of
various types is available in SQL also
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g
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g
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g
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g ‘2001-02-02’
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Operators in SQL:
The following are the commonly used operators in SQL
1
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Relational Operators =, , <=,>=,<>
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