Flashback Technology in Oracle :

Oracle Flashback Technology is a group of Oracle Database features that let you view past states of database objects or to return database objects to a previous state without using point-in-time media recovery.

Today we will see following feature of Flashback Technology :
1. Oracle Flashback Query .
2. Flashback Version Query.
3. Flashback Table.
4. Flashback Drop.

1. Oracle Flashback Query :

It is used to view committed data as it existed at some point in the past . Select command with AS OF clause references a time in the past through a time stamp or SCN.

I am updating 8 rows in the table

Here we can see updated result.

Now lets check Flashback Query AS OF clause feature

We can see the difference in above query , updation has not affected at 12:40 am.

2. Flashback Version Query :

It is used to view committed historical data for a specific time interval. Use the VERSIONS BETWEEN clause of the SELECT command.

current status of table :

Note current timestamp or SCN of database.

Lets update some records.

Check current SCN of database.

Apply version query between two SCN to see the result.

3.Flashback Table :

It is used to rewind one or more tables to their contents at a previous time without affecting other database objects.

Create one table :

Note current  SCN or timestamp.

Delete some records from the table.

check output, we can see record is deleted from the table

Note : to use flashback table feature of oracle we must enable row movement on particular table.

Now we can use flashback table feature.

see the output :

We can also use timestamp syntax

4.Flashback Drop :

Reverses the effects of dropping a table by returning the dropped table from the recycle bin to the database along with dependent objects such as indexes and triggers.

we can see table no longer exist

Now use flashback table to before drop option to reverse the effect of drop

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