user: Question: Which Frequency has a Webcast of •, and a Callsign of XEMR?
Columns: ['Frequency', 'Callsign', 'Brand', 'City of License', 'Website', 'Webcast']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [680.0, 'KKYX', 'Country Legends 680', 'San Antonio', 'kkyx.com', 'listen live']
SQL:

assistant: SELECT "Frequency" FROM "Table" WHERE "Webcast" = '•' AND "Callsign" = 'XEMR';