Simultaneously connecting to two networks with local Lan traffic to adaptor#1, & Internet traffic to adaptor#2

Question

Need simultaneous routing to two network adaptors. Computer 1 runs an Access Database which needs to quire data stored on both a private Internet connection (provided by dhcp on the first network adaptor, which gives out addresses in the 192.168.203.20x range), as well as access data on an private internal LAN (with static addresses assigned to all computers). The internal LAN computer shares are accessed as (i.e., \computer2\share1 or \192.168.1.10\share1, etc). I have head that you can set a priority for each adaptor but that requires the chosen route to time out and perhaps send the quire to the second adaptor and that is not what we need because we need to access simultaneous databases. Also, the local LAN network CANNOT be combined with the private internet network. Perhaps there is a routing table command that could direct traffic to specific Lan addresses e.g., \192.168.1.x or (\localCPU3\share3) to a specific adaptor and internet quires to the other adaptor.