using (SqlConnection connSource = new SqlConnection(csSource)) // source db
using (SqlCommand cmd = connSource.CreateCommand())
using (SqlBulkCopy bcp = new SqlBulkCopy(csDest)) { // destination db
    bcp.DestinationTableName = "SomeTable"; // destination table
    cmd.CommandText = "SELECT * FROM [Foo]"; // source table
    cmd.CommandType = CommandType.Text;
    connSource.Open();
    using(SqlDataReader reader = cmd.ExecuteReader()) {
        bcp.WriteToServer(reader);
    }
}