常用sql0926-TO_CHAR()

-- 创建以10开始的序列-- 
create sequence my_sequence start with 10;
-- 查询序列中接下来的最高值 
select my_sequence.nextval from dual;
-- create
create table student(n varchar(10));
-- insert
insert into student values(‘a‘||lpad(student_seq.nextval,9,‘0‘));
-- select
select * from student;
-- execute
execute immediate ‘set constraints all deferred‘;

--alert
ALTER TABLE student ADD UPDATETIME VARCHAR2(20);
ALTER TABLE student DROP COLUMN UPDATUSERID;


--2017/09/25


-- oracle 日期常用函數 (SYSDATE,yyyy/MM/dd)
-- TO_CHAR 是把日期或数字转换为字符串，不能指定字符串长度
-- 例如：TO_CHAR(salary,’$99,999.99’) 

SELECT * FROM acct_work_register WHERE  workflag=‘1‘ AND areatype=‘Land‘  
AND curdate<to_char(sysdate,‘yyyy/MM/dd‘) ORDER BY curdate DESC;
--2017/09/26 11:09:57
SELECT to_char(SYSDATE,‘YYYY/MM/DD HH24:MM:SS‘) FROM dual;