I would need once a month to import 12 .dbf files to SQL Server 2017. Files have dBase III version. They have a similar structure. They have no PK and no unique index and no combination of columns can be treated as unique index. Each file is around 1GB size and has 100K-300K records. Most troublesome thing is that all of them have more than 256 columns. That said all MS ODBC/OLEDB drivers fail to read them properly. The only thing I have found working so far is Devart (paid) ODBC driver. Are there any other solutions?

I have the following 2 queries.: 1. shipManagementInvoiceNetValue: SELECT IFNULL (SUM (shipManagementInvoice.netto ), 0) AS shipManagementInvoiceNetValue FROM tckopf AS shipManagementInvoice WHERE shipManagementInvoice.referenzid = 1 AND shipManagementInvoice.btyp = 5 2. shipManagementCreditNoteNetValue: SELECT IFNULL (SUM (shipManagementCreditNote.netto), 0) AS shipManagementCreditNoteNetValue FROM tckopf AS shipManagementCreditNote WHERE shipManagementCreditNote.referenzid = 1 AND shipManagementCreditNote.btyp = 6 but I need the result shipManagementInvoiceNetValue - shipManagementCreditNoteNetValue. I'm using a HXTT JDBC DBF driver that supports more than SQL92 . How can I realize that?