user: Question: 4TAB of Commercial broadcaster Radio TAB broadcasts at what frequency?
Columns: ['Callsign', 'Frequency', 'Band', 'On-air ID', 'Purpose']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['4AA', '1026', 'AM', '4MK', 'Commercial']
SQL:

assistant: SELECT "Frequency" FROM "Table" WHERE "Purpose" = 'Commercial' AND "On-air ID" = 'Radio TAB' AND "Callsign" = '4TAB';