Table: episodes_6
Columns: col
title
director
writer_s
originalairdate
repeatairdate_s
prod_code

Question: What is the original date of the repeat air date of 26/01/1969?
SQL: SELECT "originalairdate" FROM episodes_6 WHERE "repeatairdate_s" = '26/01/1969'

Question: What is the repeat date of the episode that aired 22/12/1968?
SQL: SELECT "repeatairdate_s" FROM episodes_6 WHERE "originalairdate" = '22/12/1968'

Question: who is the writer of the episode with prod.code 30-17
SQL: SELECT "writer_s" FROM episodes_6 WHERE "prod_code" = '30-17'

Question: what is the prod.code of the episode with original air date 01/12/1968?
SQL: SELECT COUNT("prod_code") FROM episodes_6 WHERE "originalairdate" = '01/12/1968'