temporal validity需要在创建表的时候使用一个vaild-time维度(包含时间起始和结束)
创建有valid-time维度的表
(1)显式指定两个date-time列
SQL> create table emp(empno number,salary number,deptid number,name varchar2(20),user_time_start date,user_time_end date,period for user_time (user_time_start,user_time_end));
(2)隐式的vaild-time列
SQL> create table emp2(empno number,salary number,deptid number,name varchar2(20), period for user_time);
vaild-time维度使用关键字"period for"指定。
如果使用隐式的valid-time列,不需要指两个日期列,oracle会创建两个隐藏列,并自动加上valid-time维度的前缀名。例如上一个例子中的前缀名是:user_time
(3)创建表之后修改表的属性
SQL> create table emp3(empno number,salary number,deptid number,name varchar2(20)); SQL> alter table emp3 add period for user_time;
valid-time列是隐藏的,默认不会显示
SQL> desc emp Name Null? Type -------------------- -------- -------------- EMPNO NUMBER SALARY NUMBER DEPTID NUMBER NAME VARCHAR2(20) USER_TIME_START DATE USER_TIME_END DATE SQL> desc emp2 Name Null? Type ------------------- -------- ---------------- EMPNO NUMBER SALARY NUMBER DEPTID NUMBER NAME VARCHAR2(20) SQL> desc emp3 Name Null? Type ------------------ -------- ----------------- EMPNO NUMBER SALARY NUMBER DEPTID NUMBER NAME VARCHAR2(20) SQL> insert into emp2(empno,salary,deptid,name,user_time_start,user_time_end) values(2,1000,20,'john2',sysdate,null); 1 row created. SQL> insert into emp3(empno,salary,deptid,name) values(3,3000,30,'john3'); 1 row created. SQL> select * from emp2; EMPNO SALARY DEPTID NAME ---------- ---------- ---------- -------------------- 2 1000 20 john2 1 row selected. SQL> select * from emp3; EMPNO SALARY DEPTID NAME ---------- ---------- ---------- -------------------- 3 3000 30 john3 1 row selected. SQL> select empno,salary,deptid,name,user_time_start,user_time_end from emp2; EMPNO SALARY DEPTID NAME USER_TIME_START USER_TIME_END ---------- ---------- ---------- -------------------- ---------------------------------------- ---------------------------------------- 2 1000 20 john2 03-NOV-15 06.15.12.000000 AM +08:00 1 row selected. SQL> select empno,salary,deptid,name,user_time_start,user_time_end from emp3; EMPNO SALARY DEPTID NAME USER_TIME_START USER_TIME_END ---------- ---------- ---------- -------------------- ---------------------------------------- ---------------------------------------- 3 3000 30 john3 1 row selected. SQL>