Note_Tech

All technological notes.

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Flashback - Flashback Query

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• Flashback - Flashback Query
  • Flashback Query

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Flashback Query

• Flashback Query:

  • Query all data as it existed at a specific point in time.
  • useful for analyzing a data discrepancy 差异.

• SELECT ... AS OF <time_stamp/SCN>

• Common Function:

  • SCN_TO_TIMESTAMP: Returns the approximate timestamp associated with a specified SCN
  • TIMESTAMP_TO_SCN: Returns the approximate system change number (SCN) associated with a specified timestamp

• Example:

SELECT employee_id, salary FROM employees
AS OF TIMESTAMP <T1>
WHERE employee_id = 200

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