How do views work in sql server

For better understanding, please have a look at the following query. Here, we are using a single table as well as we are also using the Count aggregate function which makes the view a complex view and also restricts us to perform any DML operations.

Yes, you can drop a table even if any dependent views are associated with it, but the views that are associated with it will not be dropped. They will still execute in the database only with the status as inactive object and all those views become active and start functioning provided the table is recreated.

Yes, in SQL server views can be updated. However, updating a view that is based on multiple tables, may not update the base tables correctly.

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Very useful post. You said …we cannot perform DML operations so that a complex view is also called the non-updatable or static view. If you post with an example which is very helpful.. I received a question from one of the interviewer that,you can update a view which is a simple view.. Please check our Complex View article where we explained it very clearly. A view consists of a SELECT statement, and when you run a query against the view, you see the results of it like you would when opening a table.

Views are referred to as virtual tables because they can pull together data from multiple tables, as well as aggregate data, and present it as though it is a single table. A view can be useful when there are multiple users with different levels of access, who all need to see portions of the data in the database but not necessarily all of the data. Views can do the following:. We'll now create a view from our previous query. Also add a semicolon to the end of the statement, as a statement terminator more on that below.

In this example I added a semicolon to the end of the view. Besides the standard role of basic user-defined views, SQL Server provides the following types of views that serve special purposes in a database. Indexed Views An indexed view is a view that has been materialized. This means the view definition has been computed and the resulting data stored just like a table. You index a view by creating a unique clustered index on it. Indexed views can dramatically improve the performance of some types of queries.

Indexed views work best for queries that aggregate many rows. They are not well-suited for underlying data sets that are frequently updated. Partitioned Views A partitioned view joins horizontally partitioned data from a set of member tables across one or more servers. This makes the data appear as if from one table. A view that joins member tables on the same instance of SQL Server is a local partitioned view.

System Views System views expose catalog metadata. You can use system views to return information about the instance of SQL Server or the objects defined in the instance.

For example, you can query the sys.