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

Chapter 3: The Foundation Statements of T-SQL
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And you come up with this:
SalesOrderID
------------ -----------
43660 1
43670 2
43672 6
(3 row(s) affected)
What if, however, we wanted both the MIN and the MAX? Simple! Just use both in your query:
SELECT SalesOrderID, MIN(OrderQty), MAX(OrderQty)
FROM Sales.SalesOrderDetail
WHERE SalesOrderID IN (43660, 43670, 43672)
GROUP BY SalesOrderID;
Now, this will yield an additional column and a bit of a problem:
SalesOrderID
------------ ----------- -----------
43660 1 1
43670 1 2
43672 1 6
(3 row(s) affected)
Can you spot the issue here? We’ve gotten back everything that we’ve asked for, but now that we have
more than one aggregate column, we have a problem identifying which column is which. Sure, in this
particular example we can be sure that the columns with the largest numbers are the columns generated
by the MAX and the smallest by the MIN. The answer to which column is which is not always so apparent,
so let’s make use of an alias. An alias allows you to change the name of a column in the result set, and
you can create it by using the AS keyword:
SELECT SalesOrderID, MIN(OrderQty) AS MinOrderQty, MAX(OrderQty) AS MaxOrderQty
FROM Sales.SalesOrderDetail
WHERE SalesOrderID IN (43660, 43670, 43672)
GROUP BY SalesOrderID;
Now our results are somewhat easier to make sense of:
SalesOrderID MinOrderQty MaxOrderQty
------------ ----------- -----------
43660 1 1
43670 1 2
43672 1 6
(3 row(s) affected)
It’s worth noting that the AS keyword is actually optional. Indeed, there was a time (prior to version 6.5
of SQL Server) when it wasn’t even a valid keyword. If you like, you can execute the same query as