SQL Alter View
View is a virtual and imaginary table come out as result -set of an SQL statement. A virtual table contains rows and columns, as same as real table. In SQL Alter View is used to modify a previous created view. The advantage of Alter View hardly any effect on dependent procedure, trigger and change permissions.
Understand with Example
The Tutorial illustrates an example from SQL Alter View. In this Tutorial, we want to describe you how to alter a created view. For, this we create a table 'Stu_Table' using create statement. The insert into add the records or rows to the created table'Stu_Table'.The select statemet return you all the record added by the insert into statement.
Create Table Stu_Table
create table Stu_Table(Stu_Id integer(2), Stu_Name varchar(15), Stu_Class varchar(10))
Insert data into Stu_Table
insert into Stu_Table values(1,'Komal',10); insert into Stu_Table values(2,'Ajay',10); insert into Stu_Table values(3,'Rakesh',10); insert into Stu_Table values(4,'Bhanu',10); insert into Stu_Table values(5,'Santosh',10); insert into Stu_Table values(6,'Tanuj',10); |
Stu_Table
Stu_Id | Stu_Name | Stu_Class |
1 | Komal | 10 |
2 | Ajay | 10 |
3 | Rakesh | 10 |
4 | Bhanu | 10 |
5 | Santosh | 10 |
6 | Tanuj | 10 |
Create View
Now we create a view of table 'Stu_Table'. The view "Stu_View" lists all the field from the "Stu_View" table. The view can be created with the help of given SQL Query.
CREATE VIEW Stu_View( Stu_id, Stu_Name, Stu_Class) AS SELECT Stu_id, Stu_name, Stu_class FROM Stu_Table |
View Stu_View
You can see the created view "Stu_View" using View Stu_View statement.
Stu_Id | Stu_Name | Stu_Class |
1 | Komal | 10 |
2 | Ajay | 10 |
3 | Rakesh | 10 |
4 | Bhanu | 10 |
5 | Santosh | 10 |
6 | Tanuj | 10 |
Alter View
The Alter View modify the existing created view Stu_View. The ALTER VIEW statement is used to modify the Stu_View enlisted all the list of field selected in select query. The WHERE clause restrict the select query and return you the record based upon condition whose stu_Id is less than equal to'5'.
ALTER VIEW Stu_View(Stu_id,Stu_Name,Stu_Class) AS SELECT stu_id, stu_name, stu_class FROM Stu_Table where Stu_Id <=5 |
View Stu_View
Stu_Id | Stu_Name | Stu_Class |
1 | Komal | 10 |
2 | Ajay | 10 |
3 | Rakesh | 10 |
4 | Bhanu | 10 |
5 | Santosh | 10 |