user: Question: What is Karen Handel polling at in the InsiderAdvantage poll where John Oxendine is at 15%?
Columns: ['Poll source', 'Dates administered', 'John Oxendine', 'Karen Handel', 'Nathan Deal', 'Eric Johnson', 'Ray McBerry', 'Undecided']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Magellan Strategies', 'July 18, 2010', '12%', '38%', '20%', '17%', '3%', '7%']
SQL:

assistant: SELECT "Karen Handel" FROM "Table" WHERE "Poll source" = 'InsiderAdvantage' AND "John Oxendine" = '15%';