The bank_account table has columns named account_id (INT) and account_balance (DECIMAL).
| account_id | account_balance |
|---|---|
| 1 | 1000 |
| 2 | 5000 |
| 3 | 600 |
| 4 | 900 |
| 5 | 1200 |
Please consider the situation of transfering 100 dollars from account with account_id=2 to account with account_id=4.