+-------------------+
|     locations     |
+-------------------+
| id (PK)           |
| code (UQ)         |
| name              |
| address           |
| created_at        |
| updated_at        |
+-------------------+
         |
         | 1
         |
         | N
+-------------------+
|   inventories     |
+-------------------+
| id (PK)           |
| item_id (FK)      |
| location_id (FK)  |
| quantity          |
+-------------------+
         ^
         |
         |
         | N
         |
         | 1
+-------------------+        +----------------------+
|      items        |        |   item_barcodes      |
+-------------------+        +----------------------+
| id (PK)           |<------ | id (PK)              |
| sku (UQ)          |   1:N  | item_id (FK)         |
| name              |        | barcode (UQ)         |
| description       |        | is_primary           |
| unit              |        +----------------------+
| is_active         |
| created_at        |
| updated_at        |
+-------------------+

         |
         | 1
         |
         | N
+------------------------+
|   stock_movements      |
+------------------------+
| id (PK)                |
| item_id (FK)           |
| location_id (FK)       |
| movement_type          |
| quantity               |
| reference_type         |
| reference_id           |
| notes                  |
| created_at             |
+------------------------+


================ STO MODULE =================

+-------------------------------+
| stock_transfer_orders (STO)   |
+-------------------------------+
| id (PK)                       |
| sto_number (UQ)               |
| from_location_id (FK)         |
| to_location_id (FK)           |
| status                        |
| created_by                    |
| approved_by                   |
| created_at                    |
| updated_at                    |
+-------------------------------+
        | 1
        |
        | N
+--------------------------------------+
| stock_transfer_order_items           |
+--------------------------------------+
| id (PK)                              |
| sto_id (FK)                          |
| item_id (FK)                         |
| requested_qty                        |
| shipped_qty                          |
| received_qty                         |
+--------------------------------------+

        |
        | 1
        |
        | N
+--------------------------------------+
| stock_transfer_shipments             |
+--------------------------------------+
| id (PK)                              |
| sto_id (FK)                          |
| shipped_at                           |
| received_at                          |
| status                               |
+--------------------------------------+


================ USERS =================

+-------------------+
|       users       |
+-------------------+
| id (PK)           |
| name              |
| email (UQ)        |
| password          |
| role              |
| created_at        |
+-------------------+