Patent ID: 7676450

Claim:
A computer-implemented method comprising steps of: based on a join condition of an anti-join operation, executing the anti-join operation based on a left table and a right table; wherein said join condition is based on a joining column of said right table and a joining column of said left table; wherein executing the anti-join operation comprises qualifying rows to be returned within a result of the anti-join operation, wherein: if said right table is empty, then qualifying all rows from the left table to be returned in the result of the anti-join operation; if at least one row from the right table includes a NULL value in the joining column of the right table, then qualifying in no rows to be returned in the result of the anti-join operation; and if no row from the right table includes the NULL value in the joining column of the right table, then qualifying in those rows from the left table to be returned in the result of the anti-join operation that, based on the join condition, do not match rows from the right table and do not include a NULL value in the joining column of the left table; and wherein the steps of the method are performed by one or more computing devices.