CREATE TABLE table_38571 ("Call sign" CLOB, "Frequency MHz" FLOAT, "City of license" CLOB, "ERP W" FLOAT, "Class" CLOB, "FCC info" CLOB)

Which Frequency MHz has a ERP W of 250?
SELECT MAX("Frequency MHz") FROM table_38571 WHERE "ERP W" = '250'
SELECT MAX("Frequency MHz") FROM "table_38571" WHERE "ERP W" = '250'