Data:
| id | client_id | transaction_type | amount |
| 1 | 1 | credit | 1000 |
| 2 | 1 | debit | 100 |
| 3 | 1 | credit | 500 |
| 4 | 1 | debit | 300 |
| 5 | 2 | debit | 1000 |
| 6 | 2 | credit | 1200 |
| 7 | 3 | debit | 1000 |
| 8 | 3 | credit | 1000 |
| 9 | 4 | debit | 1000 |
Question: How we can get each client balance after each transaction?
Solution:
In PostgreSQL, Microsoft SQL Server and MySQL since version 8.0 we can WINDOW FUNCTIONS Use next links for test the above solution: PostgreSQL 12 fiddle MySQL 8.0 fiddle MS SQL 2017 fiddle Legacy MySQL server have not window function implemented, so the solution is possible using variables: Use this link for MySQL 5.7 fiddle code test