You want to use Flashback Transaction Query to identify the SQL needed to reserse a transaction in the HR.EMPLOYEES table. Where can you find out the value of the transaction ID column XID to use when you query FLASHBACK_TRANSACTION_QUERY?(Choose the best answer.)
A. From the VERSIONS_XID column of HR.EMPLOYEES
B. From LogMiner
C. From the XID column of HR.EMPLOYEES
D. From the VERSIONS_XID column of FLASHBACK_TRANSACTION_QUERY
Answer: A
Every table has the pseudo-column VERSIONS_XID that you can query for a transaction ID of a past transaction with the AS OF clause.
每个表都有伪列versions_xid可以在AS OF从句中查询过去的交易事务ID。
You need to have the XID or SCN before querying FLASHBACK_TRANSACTION_QUERY and retreive the SQL to reverse the transaction.
在查询FLASHBACK_TRANSACTION_QUERY视图检索SQL进行回退交易前, 你需要有XID或SCN。
闪回版本查询的6个伪列：VERSIONS_STARTSCN, VERSIONS_STARTTIME, VERSIONS_ENDSCN, VERSIONS_ENDTIME, VERSIONS_XID, VERSIONS_OPERATION.来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/81227/viewspace-2124934/ ，如需转载，请注明出处，否则将追究法律责任。
