Beginning Microsoft SQL Server 2008 ... - S3 Tech Training

HireDate,
TerminationDate,
ManagerEmpID,
Department
FROM Employees;
We are now ready to let everyone have access — directly or indirectly — to the data in the Employees
table. Users who have the “need to know” can now be directed to the Employees table, but we continue
to deny access to other users. Instead, the users who do not have that “need to know” can have access to
our Employees_vw view. If they want to make use of it, they do it just the same as they would against a
table:
SELECT *
FROM Employees_vw;
Views as Filters
Chapter 10: Views
This actually gets into one of the sticky areas of naming conventions. Because I’ve
been using the _vw suffix, it’s pretty easy to see that this is a view and not a table.
Sometimes, you’d like to make things a little more hidden than that, so you might
want to deliberately leave the _vw off. Doing so means that you have to use a different
name (Employees is already the name of the base table), but you’d be surprised
how many users won’t know that there’s a difference between a view and a table if
you do it this way.
This will probably be one of the shortest sections in the book. Why? Well, it doesn’t get much simpler
than this.
You’ve already seen how to create a simple view — you just use an easy SELECT statement. How do we
filter the results of our queries? With a WHERE clause. Views use a WHERE in exactly the same way.
Let’s take our Employees_vw view from the last section, and beef it up a bit by making it a list of only
current employees. To do this, only two changes need to be made.
First, we have to filter out employees who no longer work for the company. Would a current employee
have a termination date? Probably not, so, if we limit our results to rows with a NULL
TerminationDate, then we’ve got what we’re after.
The second change illustrates another simple point about views working just like queries — the column(s)
contained in the WHERE clause do not need to be included in the SELECT list. In this case, it
doesn’t make any sense to include the termination date in the result set as we’re talking about current
employees.
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