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  Pseudo Column in Oracle. Hello Everyone, Today I will discuss about Pseudo column in Oracle. This topic is very important so before going to read this blog, I suggest you to please see my previous blogs which is in archive folder for your reference so that it’s easy for you to understand this topic. Let’s discuss about Pseudo Column in Oracle. Pseudo column: A pseudo-column is dynamic in Oracle as it behaves like a table column but is not stored in the table. Pseudo column behaves like a table column, but is not actually stored in the table. You can select from pseudo columns, but you cannot insert, update, or delete their values. A pseudo column is also similar to a function without arguments. In   Simple word we can say Pseudo column is a column that yields a value when selected, but which is not an actual column of the table. An example is RowID or SysDate. It can be use in combination with the DUAL table. Below are the Pseudo Column commonly used in Oracle Dat...

                               Views and Types of View in Oracle.   Hello Everyone, In this blog I will discuss about Views and types of Views in Oracle Database .Views plays very important role in database as   Views are Virtual table that can be created from existing or base table. A view can be known as a ‘Stored Query’ or a “Virtual Table”. Views mainly used for security purpose and view used in most places where a table can be used. The table from which view is created are called based table. We can query view just like a table , but views doesn’t required disk space. A view representing a subset of the data present in a table, and performing functions such as joining and simplification of multiple tables into a single table, data aggregation, handling data complexity, providing security etc. A view can be created by SQL DDL create command i.e Create view statement View can be create...

Cursor and Types of Cursor in Oracle with Examples.   Hello Everyone, Today I will discuss about Cursor in Oracle and it’s uses in PL/SQL anonymous block. Cursor is very important part in PL/SQL .Cursor act as a pointer to this context area. PL/SQL controls the context area through a cursor. A cursor holds the rows (one or more) returned by a SQL statement. The set of rows the cursor holds is referred to as the active set. For example: The number of rows processed through multiple table and that cursor can be used in that block. For our convenient we name a cursor so that it could be referred to in a program to fetch and process the rows returned by the SQL statement, one at a time. There are three types of cursors   in Oracle ·         Implicit cursors : Maintained By Oracle Server Itself ·          Explicit cursors : Controlled by programmer so in Explicit Cursor Programmer need to follow the below step ...

  SQL SUBQUERY AND CO-RELATED SUBQUERY IN ORACLE. Hello Everyone, Today I will give you the overview of Sub query and CO-RELATED Sub Query. Before starting this topic I suggest you to please go through my previous blogs related with SQL joins and types of Join, Classification of SQL and various commands in SQL. Before knowing SUBQUERY and CO-RELATED SUBQUERY first need to understand query. Query :   A query is basically used to request data or information from database tables or combination of tables to display the result .   In another word Data will be generated as a result used by SQL (Structure Query Language). In SQL statement we use select clause to fetch the data, from clause to pull data from the table and where clause to filter the result/output. For Example : If I need student_name from student table who lives in Delhi we need to query the data from student table.   To get the result we use the below query : Select student_name from student wh...

  Aggregate Functions and Group By Clause Oracle with Examples.   Hello Everyone, Today I will   discuss about   Aggregate function in SQL by using Group By Clause and different clauses with some examples . Please go tjrough my previous blogs in Archive folder for classification of SQL, Commands and   SQL joins for your understanding.   Aggregate Functions Allows us to perform a calculation on a set of values to return a single value . We can use Group by Clause to group the result-set by one or more columns. Also we can use Having clause to restrict or filter the data as per our requirement. Note: Whenever we use Aggregate function in SQL we can’t able to use where condition. To restrict or filter the record we need to use having clause instead of Where. Below is the most commonly used Aggregate function in SQL.   MAX : Max function   used to get the maximum values in a set of values. COUNT : This function used to count rows in ...