Category: SQL

TCL commands

Transaction Control Language (TCL Commands)

COMMIT : This command is used to save the users action  until that particular point of time. Until and less commit is performed , the changes made by transaction are not made permanent. Syntax...

DML commands

Data Manipulation Language ( DML Commands)

Data Manipulation Commands are used for managing the data within the database objects. These commands are not auto commit unlike DDL commands.   Types of Data Manipulation Language ( DML Commands) : 1. SELECT...

Anonymous PLSQL block

Anonymous PL/SQL Block

Definition : The PL/SQL block that has no name is called Anonymous PL/SQL Block. Structure : Since the Anonymous Blocks have no names , therefore the header section is completely missing. They only consist...

Null Functions

Null Functions

Null Functions : Null Functions are used to handle Null values . Following different kinds of Null Functions are available in Oracle. 1. NVL Function : NVL stands for Null Value. This Function is...

Slow changing dimension in informatica

Slow Changing Dimensions in Informatica (SCD)

Defining Slow Changing Dimensions: Change in the city names for e.g. Madras to Chennai , Change in the price of the product , Changes in the residential location of the people , Changes in...

DUAl table in oracle

DUAL Table in Oracle

Defining Dual Table : DUAL is a Special table having one row and one column. The Datatype of the Column is Varchar2(1) , Column Name is ‘DUMMY’ and Value is ‘X’. It is created...

Set Operator

Set Operators

Defining Set Operators: Set Operators combine the Result Set of two or more SELECT queries into a single result. The query containing the set operator is called Complex Query. Key Facts about Set Operators...

Joins in SQL

Joins in SQL

What are Joins ? Joins may be defined as SQL queries, which are used to combine rows from two or more tables or views based on the relationship between the tables. Why and When...

Correlated Sub Queries.

Correlated Sub Queries.

Unlike the normal Subqueries, the Correlated Subqueries can also be defined as Inner Query embedded in an Outer Query. But the main difference between Correlated and Uncorrelated or normal Subquery is –