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JOINS and Types of Joins

INTRODUCTION TO JOINS

A join clause is used in relational database system to combine rows from two or more tables based on a common field between them. It is performed by using ‘where’ or ‘on’ clause in which specify the column name of both table and the condition is that data type should be same in both tables which combines the specified rows of tables.

Consider the following two tables Employees and Orders…

Data Types in ORACLE

Data Types in ORACLE The data type is used to create an object such as table, procedure and package and specify a data type for every column. It has specific storage format, constraints and a specific range of value. An oracle database has a built in data type as well as user defined data type Here are various data types used in ORACLE: Character Data type Numeric Data type Date Data type LOB Data type RAW and LONG RAW Data type ROWID and UROWID Data type Character Data type The character data type is used to store character when create the database. It includes national character set or database character set. It is less restrictive and free form text as compare than other data type. For example character can store all alphanumeric values. Types of Character data Type: Here are various data types used in character...

CONSTRAINT in Oracle

Definition of Constraint A constraint is defined in integrity constraint to specify rules for the data in a database.  If there is any violation between the constraint and the data action, the action is aborted by the constraint. It can be specified when the table is created using the CREATE TABLE statement or after the table is created using the ALTER TABLE statement. It can be specify in two ways: Column level constraint Table level constraint Column level constraint It refers to a single column in the table and do not specify the column name. It is also known as inline specification. Table level constraint It refers to one or more column in the table and specifies the names of the column to which they apply. It is also known as outline specification. Types of Constraints Oracle Database creates six types of constraints...

Multimedia Database

Introduction to Multimedia Database It is a collection of related multimedia data type such as text, images, audio and video and file types such as .txt for text, .jpg for images, .mp3 for audio, .swf for video. It facilitate for creation, storage, access, query and control of a multimedia database. It contains number of features and provides information such as engineering, science, medicine and social science. It have large amount of data that provide consistency, concurrency, integrity, security and availability of data. From a user point of view it provides functionalities for easy manipulation, query and retrieval of highly relevant information from large collection of stored data. It manage large amount of multimedia data used in software application. A Multimedia database has to provide some new and enhanced functionalities and features. Types of Multimedia Data Types The multimedia data types are categorized into three categories. Static...

Schema, Subschema and instance

Schema Schema is used to describe logical database and tell how the data is organized and how relation among them is associated. In other words it is the physical arrangement of the data as it appears in the DBMS. A database schema is plan for a database system and describes the relationship between the entity and attribute. It includes the definition of the database name, the record type and the component that make up the records. It is sometimes called as overall model of the data a conceptual model or conceptual schema. A database schema is a meta-data that means data about data and it describes the relations in a database. It is simply say as the “layout” of a database or the blueprint that describes the way data is organized into tables. The language used to describe the schema is Structured Query Language and CREATE statements is used...

Database Architecture

Introduction to Database Architecture Database architecture can be centralized, decentralized and hierarchical. The DBMS architecture divides the whole system as single tier, multi tier and n-tier architecture which can be independently modified, altered, changed or replaced. Types of Database Architecture Single -Tier Two-Tier N-Tier SINGLE TIER The single tier architecture is also called as 1-tier architecture. In 1-tier architecture user work as a server and maintain this changes itself. It does not provide support for end users and use for database designer and programmer. An example of single tier architecture is file server architecture. In this architecture a database is stored on single machine in shared location. Advantage of 1-tier architecture It is relevant to small number of users Disadvantage of 1-tier architecture It works only small amount of data Two-tier architecture The two-tier architecture is like a client-server application. The...