Oracle database tables usually contain a column known as Object Version number (OVN).
Here is its use .
This column is used to control the update patterns of a tuple. (row in the database table ).
Once the row is inserted in the table the OVN is 1.
When there is an update on the same record then it checks the value of OVN.
If the OVN is same then it commits the changes to the database and increments the value of OVN to the next number .
Some other sources when trying to update the same row finds the change in OVN and the system rejects it advises to requery the record .
This feature is absolutely helpful when there are multiple updates and only 1 update is allowed at a time .
Even the APIs use this as a parameter: p_object version_number.
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