SQL Server View interview questions and answers

What is a View in SQL Server?

A View is a virtual table that is based on the result of a query. It does not store any data on its own but rather displays the data from one or more tables. Views can be used to simplify complex queries, provide a level of abstraction, restrict access to certain columns or rows, and enhance security.

What are the advantages of using Views?

There are several advantages of using Views:

• Simplify complex queries by encapsulating them into a reusable object.
• Provide a level of abstraction, allowing users to work with a subset of data without exposing the underlying table structure.
• Enhance security by restricting access to specific columns or rows.
• Improve performance by pre-computing complex joins or aggregations.

How do you create a View in SQL Server?

 To create a View, you can use the following syntax:

CREATE VIEW view_name AS

SELECT column1, column2, ...

FROM table_name

WHERE condition;

You specify the columns you want to include and define the query that retrieves the data. Optionally, you can also add a WHERE clause to filter the rows.

Can you update or insert data into a View?

Yes and no. It depends on the type of View. In SQL Server, you can update or insert data into a View if the following conditions are met:

• The View is based on a single table (not a join or complex query).
• The View contains all the NOT NULL columns from the underlying table.
• The View does not have any DISTINCT, GROUP BY, or HAVING clauses.

How can you modify an existing View?

You can modify a View in SQL Server using the ALTER VIEW statement. Here's the syntax:

ALTER VIEW view_name AS

SELECT column1, column2, ...

FROM table_name

WHERE condition;

You specify the new query or changes you want to make to the existing View.

How do you drop a View in SQL Server?

To drop a View, you can use the following statement:

DROP VIEW view_name;

This removes the View and its definition from the database.

Can you create an index on a View?

Yes, you can create an index on a View in SQL Server. It's called an Indexed View or Materialized View. However, there are certain requirements that must be met, such as the View must have a unique clustered index, the underlying tables must have certain characteristics, and the View must be schema-bound.

How can you check the definition of a View in SQL Server?

You can use the following system catalog views to retrieve the definition of a View:

SELECT VIEW_DEFINITION

FROM INFORMATION_SCHEMA.VIEWS

WHERE TABLE_NAME = 'view_name';

This query will return the definition of the specified View.

These are some common interview questions related to SQL Server Views. It's important to note that the specific questions asked may vary, and it's always a good idea to study and prepare based on the job requirements and the level of expertise expected.