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ISAS PRESENTATION ON : 

ISAS PRESENTATION ON RDBMS Represented by 1

Contents : 

Contents Meaning Difference between DBMS and RDBMS Advantages Disadvantages Tables Format View Keys Normalization Three forms 2

Meaning : 

Meaning Relational Database Management system is a a type of database management system (DBMS) that stores data in the form of related tables. Relational databases are powerful because they require few assumptions about how data is related or how it will be extracted from the database. It can be defined as a database management system where all data visible to the user is organized strictly as tables of data values, and where all database operations work on these tables. A good example of a RDBMS is Microsoft SQL or MySQL. 3

Diff between DBMS AND RDBMS : 

Diff between DBMS AND RDBMS A database management system is a software used to store and manage data. A DBMS stores data in databases and uses data models to describe the various ways of organizing data. A relational database management system is an advanced version of a DBMS that also defines the relationship between the various data values. This feature helps in organizing and accessing data more efficiently than DBMS. 4

Advantages : 

Advantages Improved conceptual simplicity Easier database design, implementation, management, and use Powerful database management system 5

Disadvantages : 

Disadvantages Possibility of poor design and implementation – relational databases do not have enough storage area to handle data such as images, digital and audio/video. – the requirement that information must be in tables where relationships between entities are defined by values. 6

RDBMS(continued) : 

RDBMS(continued) We will use the terms tables and relations interchangeably. – In a RDBMS, the data is logically perceived as tables. Tables are logical data structures that we assume hold the data that the database intends to represent. Tables are not physical structures. Each table has a unique name. 7

RDBMS tables : 

RDBMS tables – Tables consist of a given number of columns or attributes. The row in the table is called a tuple . The column(or field) is called an attribute. The number of tuples is called the cardinality of the table. The number of attributes is called the degree of the table. A domain is a pool of values from which the actual values appearing in a given column are drawn. 8

General format of a relation whenrepresented as a table : 

General format of a relation whenrepresented as a table Relation: a relation is a 2D table has the following features: Name Attributes Tuples 9

Important property of relation : 

Important property of relation Relation means a tabular arrangement of data values. Each table in a database has a unique table name that identifies its contents. Every column of a table must have a name. A row cannot be identified by its position in the table. Every table must have some column that uniquely identifies each row in the table. No two columns of the same table may have identical names. 10

Views : 

Views 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). View are like windows through which you view desired information that is actually stored in a base table CREATE VIEW Good items AS (name of the view) SELECT *FROM items (name of the base table) WHERE Price>12 (condition) 11

Keys : 

Keys The word key is much used and abused in the context of relational database design Primary key Candidate key Alternate key Foreign key 12

Primary key : 

Primary key A primary key is a set of one or more attributes that can uniquely identify tuples within the relation. Every relation does have a primary key. Supp# is the primary key for suppliers as it contains unique value for each tuple in the relation. 13

Candidate key : 

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. There are two candidate keys Supp# and Supp-Name in the Suppliers relation 14

Alternate key : 

Alternate key A candidate key that is not the primary key is called an alternate key. In Suppliers table Supp-name is the alternate key 15

Foreign 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. In other words, a non key attribute of a table, which is the primary key of some other table is known as foreign key. 16

Normalization : 

Normalization Normalization is a scientific method of breaking down complex table structures into simple table structures by using certain rules. It enables faster sorting and index creation, few NULLs and makes the database easy. Rules that should be followed each table should have an identifier. each table should store data for a single type of entity. Columns should avoid NULLs should be avoided 17

The three normal forms : 

The three normal forms Normalization theory is built around the concept of normal forms. There are three normal forms are 1NF, 2NF, 3NF,Boyce-Codd Normal form(BCNF). 1Normal form= each field contains the smallest meaningful data value possible (no field with multiple values listed). Ex First name and last name as separate fields. There are NO repeating group of fields Ex one field called Month instead of 12 fields called Jan, Feb, March.. 18

Continued : 

Continued 2Normal form= each non key field in the table must relate to the entire Primary key value. Ex In this table, StudentID & CourseID make up the compound Primary key 19

continued : 

continued 3Normal form= each non key field in the table must relate directly to the single field Primary key value. Ex In this table, CourseID is the single-field Primary key. 20

conclusion : 

conclusion Here we only touched the surface of Relational Database Design. I hope the info provided here will be useful to your work and I welcome any feedback about topics for future database, Java and Internet articles. 21

Thank you : 

Thank you 22

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