oracle中sql语句的to_date语法

完整日期：TO_DATE('2009-4-28 00:00:00', 'yyyy-mm-dd hh24:mi:ss');

                   to_date('2008/09/20','yyyy/mm/dd')

创建视图语句 CREATE VIEW ViewPractice5_1 

AS（不可缺少）

select语句

对列进行操作就可以用case---- case when ....Then .. else .... end

SQL语句： 

SELECT
sum(case WHEN sale_price<1000 THEN 1 ELSE 0 end) AS low_price,
sum(case WHEN sale_price BETWEEN 1001 AND 3000 THEN 1 ELSE 0 end) AS mid_price,
sum(case WHEN sale_price>3001 THEN 1 ELSE 0 end) AS high_price
FROM PRODUCT;