Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Export (0) Print
Expand All

Exists (DMX)

Returns true if the specified sub-query returns at least one row.


EXISTS(<subquery>)

subquery

A SELECT statement of the form SELECT * FROM <column name> [WHERE <predicate list>].

Returns true if the result set returned by the subquery contains at least one row; otherwise, returns false.

You can use the NOT keyword before EXISTS: for example, WHERE NOT EXISTS (<subquery>).

The list of columns that you add to the sub-query argument of EXISTS is irrelevant; the function only checks for the existence of a row that meets the condition.

You can use EXISTS and NOT EXISTS to check for conditions in a nested table. This is useful when creating a filter that controls the data used to train or test a data mining model. For more information, see Creating Filters for Mining Models (Analysis Services - Data Mining).

The following example is based on the [Association] mining structure and mining model that you created in the Basic Data Mining Tutorial. The query returns only those cases where the customer purchased at least one patch kit.

SELECT * FROM [Association].CASES
WHERE EXISTS
(
SELECT * FROM [v Assoc Seq Line Numbers]
WHERE [[Model] = 'Patch kit'
)

Another way to view the same data that is returned by this query is to open the model in the Association viewer, right-click the itemset Patch kit = Existing, select the Drill Through option, and then select Model Cases Only.

Community Additions

ADD
Show:
© 2015 Microsoft