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    <p>You won't notice any performance impact for one-table views; SQL Server will use the underlying table when building the execution plans for any code using those views. I recommend you schema-bind those views, to avoid accidentally changing the underlying table without changing the view (think of the poor next guy.)</p> <blockquote> <p>When a table column is to be renamed</p> </blockquote> <p>In my experience, this rarely happens. Adding columns, removing columns, changing indexes and changing data types are the usual alter table scripts that you'll run.</p> <blockquote> <p>It is easier to implement derived attributes (easier than using computed columns).</p> </blockquote> <p>I would dispute that. What's the difference between putting the calculation in a column definition and putting it in a view definition? Also, you'll see a performance hit for moving it into a view instead of a computed column. The only real advantage is that <em>changing</em> the calculation is easier in a view than by altering a table (due to indexes and data pages.)</p> <blockquote> <p>You can effectively have aliases for column names.</p> </blockquote> <p>That's the real reason to have views; aliasing tables and columns, and combining multiple tables. Best practice in my past few jobs has been to use views where I needed to denormalise the data (lookups and such, as you've already pointed out.)</p> <p>As usual, the most truthful response to a DBA question is "it depends" - on your situation, skillset, etc. In your case, refactoring "everything" is going to break all the apps anyways. If you do fix the base tables correctly, the indirection you're trying to get from your views won't be required, and will only double your schema maintenance for any future changes. I'd say skip the wrapper views, fix the tables and stored procs (which provide enough information hiding already), and you'll be fine.</p>
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    1. POSQL Server 2005: Wrapping Tables by Views - Pros and Cons
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    1. CORegarding derived attributes: Perhaps the best example is when computation of derived attribute involves an UDF. With a computed column in a table, any change of the UDF is real pain in the ass.
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    2. CORegarding frequencies of changes, additions, and deletions of columns: It obviously depends on the system. In our case changes happen much more frequently than additions and deletions.
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    3. COGood point about UDFs in computed columns, I hadn't considered that. You're right, not being able to alter the function without altering the computed column first would be annoying. I still think views should be created only when needed, rather than as a standard.
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