ORACLE 11G Flashback Versions Query

从oracle 10g开始，Flashback Technologies有了很大的改进，其中的Flashback Versions Query技术可以让你轻松查看到两个时间点或scn点之间的同一数据的变动情况(必须是在flashback范围以内)。例如下面的语句可以轻松查看t_dept表中09:00:00到09:16:00之间的数据变化情况：

SQL> SELECT * FROM mis.t_sys_dept
  2  VERSIONS BETWEEN TIMESTAMP
  3  to_timestamp('2011-10-26 09:00:00','yyyy-mm-dd hh24:mi:ss') AND
  4  to_timestamp('2011-10-26 09:26:00','yyyy-mm-dd hh24:mi:ss')
  5  WHERE DEPTid=5522;

------------------------------------------------------------------------------------------------------------------------------------

deptid     deptcode     deptname   deptlevel terminated parent   flag     manager       short    depttype    sort     u8code
5522        101004       投资公司        2               0                   1          1          5697                           0                   7         TZ
5522        101004       投资公司        2               0                   1          0          5697                           0                   7         TZ

2 rows selected

 

表不能使用别名：如果在表名后面加上别名，则会报错。

SQL> SELECT * FROM mis.t_sys_dept d
  2  VERSIONS BETWEEN TIMESTAMP
  3  to_timestamp('2011-10-26 09:00:00','yyyy-mm-dd hh24:mi:ss') AND
  4  to_timestamp('2011-10-26 09:16:00','yyyy-mm-dd hh24:mi:ss')
  5  WHERE D.DEPTid=5522;

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
VERSIONS BETWEEN TIMESTAMP
*
ERROR AT line 2:
ORA-00933: SQL command NOT properly ended

 

伪列：

如果使用伪列，则不能使用*来统配表中所有的字段：

 

SQL> SELECT versions_operation,* FROM oa.t_dept
  2  VERSIONS BETWEEN TIMESTAMP
  3  to_timestamp('2011-10-26 09:00:00','yyyy-mm-dd hh24:mi:ss') AND
  4  to_timestamp('2011-10-26 09:26:00','yyyy-mm-dd hh24:mi:ss')
  5  WHERE DEPTid=5522;
SELECT versions_operation,* FROM oa.t_dept
                          *
ERROR at line 1:
ORA-00936: missing expression

SQL> SELECT *,versions_operation FROM oa.t_dept
  2  VERSIONS BETWEEN TIMESTAMP
  3  to_timestamp('2011-10-26 09:00:00','yyyy-mm-dd hh24:mi:ss') AND
  4  to_timestamp('2011-10-26 09:26:00','yyyy-mm-dd hh24:mi:ss')
  5  WHERE DEPTid=5522;
SELECT *,versions_operation FROM oa.t_dept
        *
ERROR at line 1:
ORA-00923: FROM keyword not found where expected

 

使用伪列和字段名：

SQL> SELECT deptid,deptname,versions_operation FROM oa.t_dept
  2  VERSIONS BETWEEN TIMESTAMP
  3  to_timestamp('2011-10-26 09:00:00','yyyy-mm-dd hh24:mi:ss') AND
  4  to_timestamp('2011-10-26 09:26:00','yyyy-mm-dd hh24:mi:ss')
  5  WHERE DEPTid=5522;

 DEPTID DEPTNAME    V
---------- -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
      5522 投资公司     U
      5522 投资公司     U
      5522 投资公司

 

如果要使用*来统配表中所有的字段，则必须在*前加上表名：

SQL> SELECT oa.t_dept.*,versions_operation FROM oa.t_dept
  2  VERSIONS BETWEEN TIMESTAMP
  3  to_timestamp('2011-10-26 09:00:00','yyyy-mm-dd hh24:mi:ss') AND
  4  to_timestamp('2011-10-26 09:26:00','yyyy-mm-dd hh24:mi:ss')
  5  WHERE DEPTid=5522;

------------------------------------------------------------------------------------------------------------------------------------

deptid     deptcode     deptname   deptlevel terminated parent   flag     manager       short    depttype    sort     u8code
5522        101004       投资公司        2               0                   1          1          5697                           0                   7         TZ
5522        101004       投资公司        2               0                   1          0          5697                           0                   7         TZ

2 rows selected

 

 

不知道为什么在Flashback Versions Query中不能用表的别名，难道是oracle的BUG？

 

注：关于Flashback Pseudocolumns介绍

 

VERSIONS_STARTSCN
        Starting SCN when the row was first created. This identifies the SCN when the data first took on the values displayed in the row version.If NULL, the row version was created before the lower time bound of the query BETWEEN clause.

VERSIONS_STARTTIME
        Starting TIMESTAMP when the row version was first created. This identifies the time when the data first took on the values displayed in the row version. If NULL, the row version was created before the lower time bound of the query BETWEEN clause.

VERSIONS_ENDSCN
        Ending SCN when the row version expired. This identifies the row expiration SCN. If NULL, then either the row version is still current or
the row corresponds to a DELETE operation.

VERSIONS_ENDTIME
        Ending TIMESTAMP when the row version expired. This identifies the row expiration time. If NULL, then either the row version is still current
or the row corresponds to a DELETE operation.

VERSIONS_XID
        Identifier of the transaction that created the row version.

VERSIONS_OPERATION

        This is the operation performed by the transaction that modified the data. The values are I for insertion, D for deletion, or U for update.