The given SQL database records activity from a hypothetical application, likely involving employees submitting, approving, or rejecting declarations and handling payment requests. There are four key types of activities that follow each other:

1. **Submission**: This activity happens when an employee submits a declaration for approval by another person or entity (e.g., ADMINISTRATION). 

2. **Approval**: When the supervisor or administrator approves the submission, it goes to the next step.

3. **Final Approval**: Once the final approval is granted, the document moves into "FINAL_APPROVED" status and cannot be changed.

4. **Handling Payment**: The process may involve payment handling or receiving funds in some cases, denoted by "Payment Handled".

5. **Request for Payment** - This activity might be a request to handle payment. There could also be situations where the declaration has already been handled but needs a payment request to proceed.

The direct follow-up activities include:

- **Submission**: when an employee submits a declaration (initial submission).

- **Approval**: When the supervisor or administrator approves this first step of approval.

- **Final Approval**: This is the final action, when it's determined that everything is approved and there are no pending changes to this document.

- **Payment Handling**: If payment handling follows approval steps, then this indicates the status of the payment process after a decision has been made.

- **Request for Payment**: In situations where there is still need for funds transfer, or when a declaration requires financial action, such as issuing invoices, bills, or receipts, the "Request for Payment" activity might follow this path. 

The constraints mentioned are related to some of these activities being mutually exclusive - e.g., only one of Approval, Final Approval, Handling payment, Request for Payment can be in progress at a time. This suggests that the application is likely tracking multiple stages of approval and handling, which could include aspects like financial transactions.

In summary, this database seems to track different stages of an approval process within an organization. The submission step represents when things start, and then it flows through approvals, final approval, and payment actions at various points in time until a decision is made or something happens that requires action (e.g., requesting payment).