1) Add MonetDb driver to User Data Sources in ODBC Data Source Administrator
2) Add this reference in your project
using System.Data.Odbc;
3) Create a OdbcConnection using driver name
var monetDbC = new OdbcConnection(@"Driver={MonetDB ODBC Driver};HOST=YourServerName;PORT=50000; Database=YourDBName;UID=monetdb; PWD=monetdb;");
4) Query to MonetDB
var odbcCmd = new OdbcCommand() { Connection = monetDbC };
monetDbC.Open();
odbcCmd.CommandText = query;
odbcCmd.ExecuteNonQuery();