In process model, I have update view with populated data i need to store copy as old version before save/submit

As a best practice, maintain a history table in DB, which records the changes.

yes, I want to maintain historic table but how to design process model ? How to design and write ?

The changes to be done on DB side.

Create triggers on the existing table and insert the values into a new history table.
I am not sure about the syntaxes, https://mariadb.com/kb/en/trigger-overview/ should be helpful.

From Appian - You can then simply query the history table

As other users have mentioned, you may wish to use your underlying database to do the heavy lifting of data version management.

You may also wish to have a history table that allows you to insert the old copy of the data as a historical copy and update the current data into the current version table.  In order to do that you might take several approaches:

1)  Have two Write to Data store node entries (which may even be parallel flows) that write the old copy and update the current data.
3) Use a write to Multiple Data Store node to do both of those jobs in one node. 

I prefer the first option for any analysts and future maintainers, because it's easy to label two nodes meaningfully, but one node would require a little investigation to understand.

From a CDT perspective, it might look like this:

Main table:

• {   id: 1, firstName: "Richard", lastName: "Nolan"  }

History Table:

• { id: 1, recordId:1, firstName: "Rich", lastName: "Nolan", dateModified: "01-09-2021"},
• { id: 2, recordId:1, firstName: "Rich", lastName: "Noland", dateModified: "12-26-2020"},
• { id: 3, recordId: 12, firstName: "Mark", lastName: "Smith", dateModified: "11-17-2020" }

You could then always select data from the history table by recordId and order by dateModified to see the historical changes to a given record in the main table.

It might look like this: 

If you feel like you need to do some error checking, you could probably evaluate the success of the first write before performing the second.