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

Chapter 4: JOINs
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What I’m trying to get across here is that the table that comes before the JOIN keyword is considered to
be the LEFT table, and the table that comes after the JOIN keyword is considered to be the RIGHT table.
OUTER JOINs are, as I’ve said, inclusive in nature. What specifically gets included depends on which
side of the join you have emphasized. A LEFT OUTER JOIN includes all the information from the table
on the left, and a RIGHT OUTER JOIN includes all the information from the table on the right. Let’s put
this into practice with a small query so that you can see what I mean.
Let’s say we want to know what all our special offers are, the amount of each discount, and which products,
if any, can have them applied. Looking over the AdventureWorks2008 database, we have a table
called SpecialOffer in the Sales schema. We also have an associate table called SpecialOfferProduct
that lets us know what special offers are associated with what products:
Sales.SpecialOffer Sales.SpecialOfferProduct
SpecialOfferID SpecialOfferID
Description ProductID
DiscountPct rowguid
Type ModifiedDate
Category
StartDate
EndDate
MinQty
MaxQty
rowguid
ModifiedDate
We can directly join these tables based on the SpecialOfferID. If we did this using a common INNER
JOIN, it would look something like:
SELECT sso.SpecialOfferID, Description, DiscountPct, ProductID
FROM Sales.SpecialOffer sso
JOIN Sales.SpecialOfferProduct ssop
ON sso.SpecialOfferID = ssop.SpecialOfferID
WHERE sso.SpecialOfferID != 1