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A view in Structured Query Language (SQL) is essentially a virtual table that is based on the result-set of an SQL statement. In other words, it is a saved query that you can treat as a standalone table. Views are particularly beneficial as they can simplify query execution, provide an extra level of data security, and facilitate datasheet modifications.
Creating a View in SQL
To create a view, we use the CREATE VIEW statement followed by the name you wish to assign to the view, and a SELECT statement that fetches the data from the relevant tables.
The general syntax for creating a view in SQL is as follows:
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CREATE VIEW view_name AS SELECT column1, column2, ... FROM table_name WHERE condition; |
The conditions specified in the SELECT statement determine what data will be included in the view.
An Example of Creating a View in SQL
Let’s say we have a “Customers” table with the columns: Id, Name, City, and Country. Perhaps we want a view that only shows the customer Name and Country. Here’s how we would do it:
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CREATE VIEW Customer_Location AS SELECT Name, Country FROM Customers; |
Now, we have created a view named “Customer_Location”. We can query this view as we would any other table:
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SELECT * FROM Customer_Location; |
The result-set will be a list of customer names along with their respective countries.
Updating a View
A view can be updated under certain conditions. The syntax is as follows:
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CREATE OR REPLACE VIEW view_name AS SELECT column1, column2, ... FROM table_name WHERE condition; |
Conclusion
As you can see, views are powerful SQL functionalities that can greatly simplify your queries and data access. They can make your code cleaner and easier to maintain, and also provide a level of security by restricting access to certain data within your tables.