Good morning,
I am a database developer based in Cape Town South Africa. I written many systems in Excel, Access and SQL and have clients based in the UK, US, NZ, and Australia, as well as many local clients here in South Africa.
I wrote an invoicing system for Lawyers that is used in both NZ and SA - it keeps track of clients, matters, time recording, invoices, payments and expenses. I also wrote the database for Caxton books to store their stock inventory which in turn then creates orders for pupils at various Western Cape schools. Last year I created an inventory database for a UK based client, also for school materials which enabled the client to send out quotes and then invoices from the quotes.
For this project, a front end Access app can be created that contains user friendly forms to enter and edit inventory items. You say you wish to create an invoice - but you also want it to link to an existing invoice system? How do you envisage this working. The system at Caxton books creates quotes which can be sent to the client via email, and then an invoice can be created from that quote?.
Multiple reports can be created based on the data in the table and can be filtered by item, client, sale/transaction date, items in stock etc.
Thanks for your consideration.
Mel