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SQL - VIEW AND DUAL

SQL - VIEW SQL - DUAL: Here, we will learn what is VIEW, how to create VIEW and how it reflects on the tables?
Submitted by Shubham Singh Rajawat, on November 14, 2017

A VIEW is a virtual table, through wish we can select a small portion of data from one or more table, and it restricts the access on the original table/data. Any changes done on data in view will reflect on the tables from which data is taken.

A DUAL is a special one column and one row which can be used to do small calculations and operations etc.

Sample table (Student),

alter table in sql example

Examples:

1) Create a view from the student table

CREATE VIEW first_view AS SELECT student_name, City from Student;

To view this table we need to use SELECT query.

SELECT * FROM first_view;

Here, first_view : it is the name of the virtual table

views in sql example

2) Use DUAL to get current date

SELECT SYSDATE() FROM DUAL;

Will return current date from the system.

SQL - DUAL in sql example




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