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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...