Patent Document ID: 9886481
Application ID: 13278095

Base Claim:
1. A method, comprising: identifying, in a first query, a first expression that includes a column name identifying a table column; and rewriting said first query to form a second query that includes a conditional expression that returns a value from the table column only when a condition is satisfied; wherein rewriting said first query to form said second query includes creating: (a) a second expression that includes a first alias that refers by said column name to said conditional expression, and (b) a third expression that includes a second alias that refers to said table column; wherein the method is performed by one or more computing devices.

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Claim 9:
9. The method of claim 1 , wherein the third expression is a clone of the first expression, wherein the second query includes a predicate that conjunctively joins the third expression with the second expression that is derived based on both the first expression and an access control policy, and wherein the conditional expression returns null when the condition is not satisfied.