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

Chapter 4: JOINs
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vendor. We’re going to go ahead and start aliasing from the beginning, since we will want to do this in
the end:
USE Chapter4DB
SELECT v.VendorName
FROM Vendors v
This yields a scant three records:
VendorName
---------------------------------------
Don’s Database Design Shop
Dave’s Data
The SQL Sequel
(3 row(s) affected)
These are the names of every vendor that we have at this time. Now let’s add in the address information
— there are two issues here. First, we want the query to return every vendor no matter what, so
we’ll make use of an OUTER JOIN. Next, a vendor can have more than one address and vice versa, so the
database design has made use of an associate table. This means that we don’t have anything to directly
join the Vendors and Address tables — we must instead join both of these tables to our linking table,
which is called VendorAddress. Let’s start out with the logical first piece of this join:
SELECT v.VendorName
FROM Vendors v
LEFT OUTER JOIN VendorAddress va
ON v.VendorID = va.VendorID
Because VendorAddress doesn’t itself have the address information, we’re not including any columns
from that table in our SELECT list. VendorAddress’s sole purpose in life is to be the connection point of a
many-to-many relationship (one vendor can have many addresses and, as we’ve set it up here, an address
can be the home of more than one vendor). Running this, as we expect, gives us the same results as before:
VendorName
--------------------------------------
Don’s Database Design Shop
Dave’s Data
The SQL Sequel
(3 row(s) affected)
Let’s take a brief time-out from this particular query to check on the table against which we just joined.
Try selecting all the data from the VendorAddress table:
SELECT *
FROM VendorAddress