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7 30 1.00
7 45 0.50
7 50 3.00
7 60 4.00
10 10 2.00
10 20 1.50
10 30 1.00
10 4 1.50
10 50 3.00
10 60 4.00
43 50 3.00
44 50 3.00
47 10 1.00
47 20 1.00
47 50 3.50
48 10 1.00
48 20 1.00
48 50 3.50
53 50 0.50
66 50 1.75
67 50 1.00
(23 row(s) affected)
As you can see, we are getting back multiple rows for many of what were originally a single row in the
ProductModel table. For example, ProductModelID 7 had six different instances of the Location element,
so we received six rows instead of just the single row that existed in the ProductModel table.
While this is, perhaps, the most complex of the various XML data type methods, the power that it gives
you to transform XML data for relational use is virtually limitless.
.exist
.exist works something like the EXISTS statement in SQL. It accepts an expression (in this case, an
XQuery expression rather than a SQL expression) and will return a Boolean indication of whether the
expression was true or not. (NULL is also a possible outcome.)
If, in our .modify example, we had wanted to show rows that contain steps that had spec elements, we
could have used .exist:
WITH XMLNAMESPACES (‘http://schemas.microsoft.com/sqlserver/2004/07/
adventure-works/ProductModelManuInstructions’ AS PI)
SELECT ProductModelID, Instructions
FROM Production.ProductModel
WHERE Instructions.exist(‘/PI:root/PI:Location/PI:step/PI:specs’) = 1
Pay particular attention to the point at which the test condition is being applied!
Chapter 16: A Brief XML Primer
For example, the code would show us rows where at least one step had a spec element in it — it does not
necessarily require that every step have the spec element. If we wanted every element to be tested, we
would either need to pull the elements out as individual rows (using .nodes) or place the test condition
in the XQuery.
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