Export a Magento database without the products or without the categories, place this file in app/etc/. Docs about creating a custom dump command: https://github.com/netz98/n98-magerun/wiki/Stripped-Database-Dumps

n98-magerun.yaml

commands:
  N98\Magento\Command\Database\DumpCommand:
    table-groups:
      - id: products
        description: Skip all product tables.
        tables: >
                catalog_category_product*
                catalog_compare_item
                catalog_product_*
                cataloginventory_stock_*
                catalogrule_affected_product
                catalogrule_product*
                catalogsearch_*
      - id: categories
        description: Skip all category tables.
        tables: >
                catalog_category_*