Friday, October 28, 2011
ORACLE SQL TUTORIAL: FLASHBACK QUERY
Used to retrieve the data which has been already committed with
out going for recovery.
Flashbacks are of two types
Ø Time base flashback
Ø SCN based flashback (SCN stands for System Change Number)
Ex:
1) Using time based flashback
a) SQL> Select *from student;
-- This will
display all the rows
b) SQL> Delete student;
c) SQL> Commit; -- this will commit the work.
d) SQL> Select *from student;
-- Here it will
display nothing
e) Then execute the following procedures
SQL> Exec
dbms_flashback.enable_at_time(sysdate-2/1440)
f) SQL> Select *from student;
-- Here it will
display the lost data
-- The lost data will come but the current system time was used
g) SQL> Exec dbms_flashback.disable
-- Here we have to disable the flashback to
enable it again
2) Using SCN based flashback
a) Declare a variable to store SCN
SQL> Variable s number
b) Get the SCN
SQL> Exec :s := exec dbms_flashback.get_system_change_number
c) To see the SCN
SQL> Print s
d) Then execute the following procedures
SQL> Exec
dbms_flashback.enable_at_system_change_number(:s)
SQL> Exec dbms_flashback.disable
Do you think this Article is useful?
Subscribe to:
Post Comments (Atom)
2 Responses to “ORACLE SQL TUTORIAL: FLASHBACK QUERY”
October 8, 2016 at 12:59 AM
Regards
Sridevi Koduru (Senior Oracle Apps Trainer Oracleappstechnical.com)
LinkedIn profile - https://in.linkedin.com/in/sridevi-koduru-9b876a8b
Please Contact for One to One Online Training on Oracle Apps Technical, Financials, SCM, SQL, PL/SQL, D2K at training@oracleappstechnical.com | +91 - 9581017828.
October 13, 2021 at 3:10 AM
JavaScript is among the most powerful and flexible programming languages of the web. It powers the dynamic behavior on most websites, including this one. You will learn programming fundamentals and basic object-oriented concepts using the latest JavaScript syntax. The concepts covered in these lessons lay the foundation for using JavaScript in any environment. free course to learn Microservice
Post a Comment