Rediger

ReuseWhere function

The WHERE clause in a query specifies a set of items to match results against. Subsequent queries can share the work performed for a previous query by using the ReuseWhere function in a new query WHERE clause. Queries that take advantage of this function execute faster.

Examples

The following scenario shows how to use the ReuseWhere function:

  1. You issue the following query:

    SELECT System.ItemName FROM SystemIndex 
WHERE CONTAINS(*, 'pencil') AND System.ItemDate > '2007-3-5'

  2. From the returned rowset, you get a Where ID, Query1WhereID.

    The Where ID is a rowset property with PROPSET {aa6ee6b0-e828-11d0-b2-3e-00-aa-00-47-fc-01 }, PROPID 8, and type UI4.

  3. You issue a second query with the ReuseWhere function, passing in the Query1WhereID from step 2:

    SELECT System.ItemUrl FROM SystemIndex 
WHERE ReuseWhere(Query1WhereID) AND SCOPE='file:'

The second query is equivalent to the following:

SELECT System.ItemUrl, System.ItemName FROM SystemIndex 
WHERE CONTAINS(*, 'pencil') AND System.ItemDate > '2007-3-5' AND Scope='file:'

The ReuseWhere function can be used anywhere in the WHERE clause.

Reference

WHERE Clause

Rowset Properties

 

 

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