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

Chapter 3: The Foundation Statements of T-SQL
Note that if you try running a SELECT against @MyTable by itself (that is, outside
this script), you’re going to get an error. @MyTable is a declared variable and it exists
only as long as our batch is running. After that, it is automatically destroyed.
It’s also worth noting that we could have used what’s called a temporary table. This
is similar in nature, but doesn’t work in quite the same way. We will revisit temp
tables and table variables in Chapters 11 through 13.
Changing What Y ou’ve Got with the
UPDATE Statement
The UPDATE statement, like most SQL statements, does pretty much what it sounds like it does — it
updates existing data. The structure is a little bit different from a SELECT, although you’ll notice definite
similarities. Like the INSERT statement, it has a fairly complex set of options, but a more basic version
that will meet the vast majority of your needs.
The full syntax supports the same TOP and similar predicates that were supported under SELECT and INSERT:
UPDATE [TOP ( ) [PERCENT] ]
SET = [.WRITE(, , )]
[, = [.WRITE(, , )]]
[ OUTPUT ]
[FROM ]
[WHERE ]
Let’s look at the more basic syntax:
UPDATE
SET = [, = ]
[FROM ]
[WHERE ]
An UPDATE can be created from multiple tables, but can affect only one table. What do I mean by that?
Well, we can build a condition, or retrieve values from any number of different tables, but only one table
at a time can be the subject of the UPDATE action. Don’t sweat this one too much. We haven’t looked at
joining multiple tables yet (next chapter folks!), so we won’t get into complex UPDATE statements here.
For now, we’ll look at simple updates.
Let’s start by doing some updates to the data that we inserted in the INSERT statement section. Let’s
rerun that query to look at one row of inserted data. (Don’t forget to switch back to the pubs database.):
SELECT *
FROM Stores
WHERE StoreCode = ‘TEST’;
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