oracle函数

--创建数据表空间create tablespace DBStudy datafile 'D:\DB\oracle\DBStudy.dbf' size 100m;---给用户附表空间权限alter user king default tablespace DBStudy ;grant create session,create table,unlimited tablespace to king;use DBStudycreate table Student( stuNo varchar(12) not null, stuName varchar(20) not null, stuSex number(1), stuBrithday date default sysdate, stuAddress varchar(20))create table Scourse( scourseNo varchar(20) not null, scourseName varchar(20) not null, scourseType varchar(20))create table Score( stuNo varchar(12) not null, scourseNo varchar(12) not null, score number(3,1))select sysdate-1 from dual; select MONTHS_BETWEEN(sysdate,to_date('2012-01-30','yyyy-mm-dd')) from dual;select trunc(to_date(sysdate,'yyyy-mm-dd')) from dual;select trunc(to_date('2012-03-12','yyyy-mm-dd'),'day') from dual;select last_day(sysdate) from dualselect add_months(sysdate,3) from dual;select concat('021','51717950')||'转862' from dual;select instr('wggorkingor','or',2,2) from dual;select length('king') from dual;select replace('kwggg','wgg','in') from dual;select substr('king',2,2) from dual;select initcap('king') from dual;---创建用户CREATE USER UserName identified by UserPassword;--创建数据表空间create tablespace DBStudy datafile 'D:\DB\oracle\DBStudy.dbf' size 100m;---给用户附表空间权限alter user king default tablespace DBStudy ;grant create session,create table,unlimited tablespace to king;--oracle 数据类型1 oracle有三类数据类型：字母、数字、日期、 字母：char（length）、nchar（length）定长字符，最多存2000字节 varchar2（length）、nvarchar2（length）变长字符，最多存4000字节大对象：blob、clob、nclob、bfile可以存4gb的大字符数据数字字符：number（length，[scale])日期： year、month、day定位符：rowid返回代表行距的物理位置rownum（伪列）返回检索行顺序的数字currval返回序列的当前值nextval返回序列的下一列值数据转换：to_char：执行十字到字符和日期到字符的转换to_number：字符到数字的转换to_date:字符到日期的转换