Views in SQL Server are a powerful tool that allow you to simplify complex queries and provide a logical abstraction of your data. However, there are certain limitations that you need to be aware of when working with views.

One of the limitations of views in SQL Server is the inability to create an index on a nested view. This means that if you have a view that is built on top of another view, you cannot create an index on the outer view.

Let’s consider an example to understand this limitation. Suppose we have a view called “vw_ViewLimit1” that is created on the “SalesOrderDetail” and “TransactionHistory” tables. Now, let’s say we create another view called “vw_ViewLimit2” on top of “vw_ViewLimit1” and try to create an index on it. SQL Server will throw an error and prevent us from creating the index.

CREATE VIEW vw_ViewLimit1 AS
SELECT [SalesOrderID], [SalesOrderDetailID], [CarrierTrackingNumber], [OrderQty], sod.[ProductID], [SpecialOfferID], [UnitPrice], [UnitPriceDiscount], [LineTotal], [ReferenceOrderID]
FROM Sales.SalesOrderDetail sod
INNER JOIN Production.TransactionHistory th ON sod.SalesOrderID = th.ReferenceOrderID

CREATE VIEW vw_ViewLimit2 AS
SELECT [SalesOrderID], [SalesOrderDetailID], [CarrierTrackingNumber], [OrderQty], v1.[ProductID], [SpecialOfferID], [UnitPrice], [UnitPriceDiscount], [LineTotal], v1.[ReferenceOrderID], th.[Quantity]
FROM dbo.vw_ViewLimit1 v1
INNER JOIN Production.TransactionHistory th ON v1.SalesOrderID = th.ReferenceOrderID

CREATE UNIQUE CLUSTERED INDEX [IX_vw_ViewLimit1] ON [dbo].[vw_ViewLimit2] ([ProductID] ASC)

The error message you will receive is: “Cannot create index on view ‘vw_ViewLimit2’ because it references another view ‘vw_ViewLimit1’. Consider expanding referenced view’s definition by hand in indexed view definition.”

The reason for this limitation is that maintaining another view over a view can be complex and can lead to potential issues. However, there is a simple workaround for this limitation. Instead of creating a nested view, you can bring the code of the inner view into the outer view. By doing this, you can create an index on the outer view without any issues.

It is important to be aware of this limitation when working with views in SQL Server. By understanding the limitations, you can make informed decisions and design your database schema accordingly.

Do you know about this limitation of SQL Server views? Let us know in the comments!