If you need an inventory program with MultiLevel BOM capability but don't want the expense or associated running costs of a fully loaded ERP/MRP package then MiniMRP may be the answer you're looking for.
Inventory, purchase order, customer order, work order, Bill of Materials and shortage forecasting are all included. The 'Standard' edition of MiniMRP is ideal for single users or work groups where all users work on the name local area network sharing the same local database.
The 'Professional' edition includes additional enterprise features such as the ability to manage inventory and orders etc in multiple site/warehouses. It can also upscale to use SQL Server instead of the default/local database. Microsoft SQL Server, MySQL and MariaDB Server are all supported.