學習筆記6.8
阿新 • • 發佈:2019-01-01
SELECT prod_name FROM Products; SElECT prod_id,prod_name,prod_price FROM Products; SELECT * FROM Products; SELECT DISTINCT vend_id--取不同 FROM Products; select * from (select rownum rn,Products.prod_name from Products) where rn <=5; SELECT prod_name FROM Products WHERE ROWNUM <=5;--前5列 select prod_name from Products where rownum <= 9 minus select prod_name from Products where rownum <= 4;--5-9列 select* from Products where rownum <= 9 minus select * from Products where rownum <= 4;--5-9列 --字典序 SELECT prod_name FROM Products ORDER BY prod_name; SELECT prod_name,prod_id,prod_price FROM Products ORDER by prod_price,prod_name; --第一行決定出場順序,第二行是第一,二關鍵字,可以用第一行的相對位置表示。 SELECT prod_name,prod_id,prod_price--決定出場順序 FROM Products ORDER by 3,2; --指定降序排序 SELECT prod_id,prod_price,prod_name FROM Products ORDER by prod_price DESC,prod_id DESC;