Usually you should have two ports on the firewall, WAN1 and WAN2, which will support two Internet connections.
About how to separate the traffic between the two connections, there are several ways to do it:
1. Use port forward, there will be two different public address for two connections, use port forward to map different service you have to different connections. For example, you have 184.108.40.206 for conn1, 220.127.116.11 for conn2, you can set up port forward to map Oracle server port 1521 to IP 18.104.22.168; map Web server port 80 to 22.214.171.124
2. Use NAT, on the firewall, set up NAT to map different servers to different public address of different conn. Suppose your Oracle server is 192.168.0.1, web server is 192.168.0.10, then you can NAT 192.168.0.1~9 to 126.96.36.199, NAT 192.168.0.10~192.168.0.20 to 188.8.131.52.
hope this is helpful!