1.[代码]Oracle日期和分页

select * from li.books where book_publish_date between '1-2月-2005' and '1-2月-2010';

select * from books where book_price between 50 and 60;

select * from books where catalog_id in (select catalog_id from catalogs where catalog_name='数据库');

select * from catalogs;

---dual 表

select * from dual;

-获取oracle 的系统日期

select sysdate from dual;

--为前日期增加10天

select sysdate+10 from dual;

select (select from dual)+10 from dual;

--日期函数

select add_months(sysdate,4) from dual;

select add_months('2-2月-1990',4) from dual;

-获取指定月份的最后一天

select last_day(sysdate) from dual;

select last_day('2-2月-2014') from dual;

---计算两个月之间相差几个月

select months_between(sysdate,'27-4月-2014') from dual;

----日期的四舍五入

---按年

select round(sysdate,'year') from dual;

--按月

select round(sysdate,'month') from dual;

select round((select to_date('1987-4-15','yyyy-MM-dd') from dual),'month') from dual;

select to_date('1987-3-1','yyyy-MM-dd') from dual

--按周

select round(sysdate,'day') from dual;

--next_day 的使用， 获取指定日期的下一天所在的日期

select next_day(sysdate,2) from dual; 下一周的第几天;

select next_day('27-8月-2014',2) from dual;

--阶段当前日期

--按年

select trunc(sysdate,'year') from dual;

--按月

select trunc(sysdate,'month') from dual;

--按周

select trunc(sysdate,'day') from dual;

--比较一组数字中的最大值

select greatest(12,22,33,13,45,5) from dual;

select greatest (

'12-5月-2014',

'12-12月-2011',

'12-3月-2000'

) from dual;

---字符串函数的使用

--截断字符串(从第N个字符开始截取，截取的长度为M个字符)

select substr('helloworld',3,5) from dual;

--获取指定字符串中的字符位置

select instr('hello','o') from dual;

--获取字符串的长度

select length('liuhuahua') from dual;

--转换函数

--将其他类型的数据转为字符串(最常用的是日期转字符串)

--日期转字符串

select to_char(sysdate,'yyyy-mm-dd') from dual;

select sysdate from dual;

--将数字转为字符串

select to_char(9898.33,'$99999.999') from dual;

--将其他数据转为日期格式(通常是将字符串转为日期)

select to_date('1987-3-1','yyyy-MM-dd') from dual;

--日期比大小，获取一组日期的最大值

select greatest(

to_date('2024-4-22','yyyy-MM-dd'),

to_date('2024-5-1','yyyy-MM-dd'),

to_date('2014-12-22','yyyy-MM-dd')

) from dual;

select '4'+'5' from dual;

select 4+5 from dual;

--获取用户的登陆ID

select uid from books;

select user from dual;

--聚合函数

select sum(book_price) from books;

select count(book_id) from books;

---oracle的分页显示

select * from (select books.* ,rownum r from books where rownum<=6) where r>2;

select books.*, rownum from books where rownum<=5;

---group by

select catalog_id from books order by catalog_id;

select * from books;

---having

select catalog_id,sum(book_price) from books group by catalog_id having sum(book_price)>=100 order by catalog_id;