For RDBMS, Firebird SQL has managed to survive well in this sphere, for all of it's warts.
You can run it either as an embedded DLL or as a standalone server, and changing between the two is often just a connection string change; It seems to be fairly popular in the POS space for this reason.
You can run it either as an embedded DLL or as a standalone server, and changing between the two is often just a connection string change; It seems to be fairly popular in the POS space for this reason.