MYSQL calculate data time span

SELECT DATEDIFF( MAX(PURCHASE_DATE),MIN(PURCHASE_DATE)) FROM
(
SELECT * FROM PURCHASING_DATA L

WHERE L.CORP_ID=2112 AND DATE_FORMAT(L.PURCHASE_DATE ,'%Y' ) = '2017') A;

 

Use MIN and MAX in MYSQL to get the maximum and minimum values ​​in the result set, DATEDIFF is used to calculate the time difference between two dates