สารานุกรมพิมพ์นานกี่ปี ?ไม่จำเป็นต้องใช้ตารางทั้งหมด
for how many years was the encyclopedia printed ?It is not neccessary to use all the tables.
 table_204_843:  id [ number]  "volume" [ number]  "year" [ text]  "names" [ text]  "articles" [ number]  "pages" [ number]  "images" [ number]  "maps" [ number] 
SELECT COUNT("year") FROM table_204_843