×

Method for transforming SQL queries

  • US 6,836,770 B2
  • Filed: 08/09/2002
  • Issued: 12/28/2004
  • Est. Priority Date: 08/09/2002
  • Status: Active Grant
First Claim
Patent Images

1. A computer-implemented method for the transformation of an SQL query comprising a WHERE clause having nested SELECT expressions, the method comprising the following steps:

  • a) iteratively transforming the nested SELECT expressions in the WHERE clause of the SQL query into a corresponding and logically equivalent first step expression whereby the first step expression is defined to comprise ThereExists expressions and associated truth-value expressions; and

    b) transforming the first step expression by iteratively applying a set of NOT removal rules to push any NOT expressions to the bottom of the first step expression tree corresponding to the first step expression, to remove the NOT expressions and to remove the ThereExists expressions, whereby the WHERE clause is transformed to an expression in which nested SELECT expressions are simplified.

View all claims
  • 9 Assignments
Timeline View
Assignment View
    ×
    ×