Definition of data structure formats.

Current:

Account

First Name
Last Name
Account Number
History

Account Event

Balance Change
Description

SQL

Accounts FirstName | LastName | AccountNumber | History (JSON text)

Optimal:

Account

First Name
Last Name
Account Number (indentifier)

Account Event

Type (transfer | deposit | withdrawal)
Receiver (if applicable)
Sender (if applicable)
Balance Change
// Description can be generated based on available info

SQL

Accounts FirstName | LastName | AccountNumber

Events Type (int) | Receiver (accountnumber) | Sender (accountnumber) | BalanceChange (double)