What's the highest frequency of the KBDR callsign?
CREATE TABLE table_name_4 (frequency INTEGER, callsign VARCHAR)
SELECT MAX(frequency) FROM table_name_4 WHERE callsign = "kbdr"
### Context: CREATE TABLE table_name_4 (frequency INTEGER, callsign VARCHAR) ### Question: What's the highest frequency of the KBDR callsign? ### Answer: SELECT MAX(frequency) FROM table_name_4 WHERE callsign = "kbdr"