Shaun J Cooper

US Patent:

6411951, Jun 25, 2002

Filed:

Dec 16, 1998

Appl. No.:

09/212558

Inventors:

Cesar A. Galindo-Legaria - Bellevue WA
Shaun J. Cooper - Seattle WA

Assignee:

Microsoft Corporation - Redmond WA

International Classification:

G06F 1700

US Classification:

707 3, 707 4, 717140

Abstract:

SQL subqueries are converted into equivalent expressions rooted by a special relational operator. The special relational operator assumes properties based on the type of the expression containing the subquery. The context of the subquery is also factored into the special relational operation. The relational operator itself is optimized, when possible, into a standard join operation. The conversion process maintains a list of parameter dependencies within the query and the relational operator utilizes this list at execution time to decrease the amount of processing required to produce the query output.