# experiment

## Purpose

The **experiment** table stores records of all scientific experiments that were, are and will be conducted on SCP entities within the facility.

It tracks experiment lifecycle, associated SCP subjects, execution state and execution data.

## Columns

| Field       | Type   | Description
|-------------|--------------|----------------------------------------------------------|
| id_exp      | BIGINT       | Unique experiment identifier (PK, AUTO_INCREMENT)
| id_scp      | MEDIUMINT    | SCP identifier associated with the experiment (FK)
| state       | ENUM         | Current lifecycle state of the experiment
| description | VARCHAR(255) | Short description of the experiment objective or purpose
| start_in    | DATETIME     | Scheduled or actual experiment start time (NULLABLE)
| ended_at    | DATETIME     | Experiment completion or termination time (NULLABLE)
|---------------------------------------------------------------------------------------|

### ENUM values
- state = ('proposed', 'approved', 'rejected', 'in_preparation','in_progress','paused','completed','failed','aborted','containment_incident','unknown')


## Relationships

- References **scp.id_scp** through **id_scp** to associate each experiment with a specific SCP entity.
- Referenced by **experiment_personnel.id_exp** to track personnel participation in experiments.
- Referenced by **experiment_dclass.id_exp** to track D-Class subject participation in experiments.
- Referenced by **experiment_report.id_exp** to store detailed results and conclusions of completed experiments.


## Rules

- `start_in` value is NULL when `state` value is 'proposed' or 'rejected'.
- `ended_at` value is NULL when `state` value is either 'proposed', 'approved', 'rejected', 'in_preparation', 'in_progress' or 'paused'.
- Experimental records are unalterable once completed for audit purposes.


## Example output

+--------+--------+-----------+------------------------------------------+---------------------+---------------------+
| id_exp | id_scp | state     | description                              | start_in            | ended_at            |
+--------+--------+-----------+------------------------------------------+---------------------+---------------------+
|      5 |      2 | completed | Controlled exploration of SCPs interior. | 2026-06-30 09:00:00 | 2026-06-30 09:59:45 |
+--------+--------+-----------+------------------------------------------+---------------------+---------------------+