CREATE TABLE table_17415 ("Train No." CLOB, "Train Name" CLOB, "Origin" CLOB, "Destination" CLOB, "Frequency" CLOB)

How often does a train leave sealdah?
SELECT "Frequency" FROM table_17415 WHERE "Origin" = 'Sealdah'
SELECT "Frequency" FROM "table_17415" WHERE "Origin" = 'Sealdah'