Create/maintain reference database of SKU's and specs

I need a relational Database initially created and then updated/maintained (this will be an ongoing job). I don’t care how it is done, whether it’s with Microsoft Access, Open Office, or a web based / cloud service. I just need to have you help me query the database to compile the required information from the appropriate columns so I can create CSV files to upload to my eCommerce store. The initial database will have 20,000 rows of SKU’s. I will provide spreadsheets of information that can be uploaded by you or by myself. I will create the columns for all the tables and designate what the primary keys need to be to link tables together. In the updating/maintenance part, you will generate reports of what information is missing from certain rows so we can fill it in. Also, you will be comparing a list of maybe 1,000 parts to the existing 20,000 or so existing SKU’s to match with what we have in the database already and what we need to create new data for. Future work will also involve creating other databases similar to this for different product categories. Please let me know if you have any questions.