Use the current user's credentials and the default port, II7.

Host=myServerAddress;Database=myDataBase;

Explicit Port Specified

Host=myServerAddress;Port=II7;Database=myDataBase;

Specific User

Host=myServerAddress;Database=myDataBase;Uid=myUsername;Pwd=myPassword;

ODBC Driver for Ingres

DSN-less

Provider=MSDASQL;DRIVER=Ingres;SRVR=xxxxx;DB=xxxxx;Persist Security Info=False;Uid=myUsername;Pwd=myPassword;SELECTLOOPS=N;Extended Properties="SERVER=xxxxx;DATABASE=xxxxx;SERVERTYPE=INGRES";

Important note!
The quota " in the string needs to be escaped using your language specific escape syntax.
c#, c++   \"
VB6, VBScript   ""
xml (web.config etc)   "
or maybe use a single quota '.

.NET Framework Data Provider for ODBC

Use an ODBC driver from .NET

Driver={any odbc driver's name};OdbcKey1=someValue;OdbcKey2=someValue;

See the respective ODBC driver's connection strings options. The .net OdbcConnection will just pass on the connection string to the specified ODBC driver. Read more here.

Ingres connection strings

Ingres .NET Data Provider

Current User