มีกี่สนาม?ไม่จำเป็นต้องใช้โต๊ะทั้งหมด
How many stadiums are there?It is not neccessary to use all the tables.
 stadium:  id [ number]  name [ text]  capacity [ number]  city [ text]  country [ text]  opening_year [ number] 
SELECT COUNT(*) FROM stadium