左右内全连接
--Oracle左右内全连接----建立测试数据create table a (id number);create table b (id number);create table c (id number);insert into a values(1);insert into a values(2);insert into a values(3);insert into b values(1);insert into b values(2);insert into b values(4);insert into c values...
通用的时间函数
--获取当前时间select sysdate from dual;--把字符转换成时间格式插入到系统insert into emp(hiredate) values(to_date('20140520123015','yyyy-mm-dd hh24:mi:ss'));--获取某天是星期几select to_char(to_date('2014-06-01','yyyy-mm-dd'),'day') from dual;--把日期格式显示为英文;select to_char(t...