Connect an application

YSQL
YCQL

YugabyteDB C# Driver

Yugabyte C# Driver for YCQL is based on DataStax C# Driver with additional smart driver features.

YugabyteDB Aeon

To use the driver's partition-aware load balancing feature in a YugabyteDB Aeon cluster, applications must be deployed in a VPC that has been peered with the cluster VPC so that they have access to all nodes in the cluster. For more information, refer to Using YCQL drivers with YugabyteDB Aeon.

Prerequisites

This tutorial assumes that you have:

installed YugabyteDB, created a universe and are able to interact with it using the YCQL shell. If not, follow the steps in Quick start.
installed Visual Studio.

Write the HelloWorld C# app

In your Visual Studio create a new Project and choose Console Application as template. Follow the instructions to save the project.

Install YugabyteDB C# Driver for YCQL

The Yugabyte C# Driver for YCQL is based on a fork of the Apache Cassandra C# Driver, but adds features unique to YCQL, including JSONB support and a different routing policy.

To install the Yugabyte C# Driver for YCQL in your Visual Studio project, follow the instructions in the README.

Create the program

Copy the contents below to your Program.cs file:

using System;
using System.Linq;
using Cassandra;

namespace Yugabyte_CSharp_Demo
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                var cluster = Cluster.Builder()
                                     .AddContactPoints("127.0.0.1")
                                     .WithPort(9042)
                                     .Build();
                var session = cluster.Connect();
                session.Execute("CREATE KEYSPACE IF NOT EXISTS ybdemo");
                Console.WriteLine("Created keyspace ybdemo");

                var createStmt = "CREATE TABLE IF NOT EXISTS ybdemo.employee(" +
                    "id int PRIMARY KEY, name varchar, age int, language varchar)";
                session.Execute(createStmt);
                Console.WriteLine("Created keyspace employee");

                var insertStmt = "INSERT INTO ybdemo.employee(id, name, age, language) " +
                    "VALUES (1, 'John', 35, 'C#')";
                session.Execute(insertStmt);
                Console.WriteLine("Inserted data: {0}", insertStmt);

                var preparedStmt = session.Prepare("SELECT name, age, language " +
                                                   "FROM ybdemo.employee WHERE id = ?");
                var selectStmt = preparedStmt.Bind(1);
                var result = session.Execute(selectStmt);
                var rows = result.GetRows().ToList();
                Console.WriteLine("Select query returned {0} rows", rows.Count());
                Console.WriteLine("Name\tAge\tLanguage");
                foreach (Row row in rows)
                    Console.WriteLine("{0}\t{1}\t{2}", row["name"], row["age"], row["language"]);

                session.Dispose();
                cluster.Dispose();

            }
            catch (Cassandra.NoHostAvailableException)
            {
                Console.WriteLine("Make sure YugabyteDB is running locally!.");
            }
            catch (Cassandra.InvalidQueryException ie)
            {
                Console.WriteLine("Invalid Query: " + ie.Message);
            }
        }
    }
}

Run the application

To run the C# app from the Visual Studio menu, select Run > Start Without Debugging.

You should see the following as the output.

Created keyspace ybdemo
Created keyspace employee
Inserted data: INSERT INTO ybdemo.employee(id, name, age, language) VALUES (1, 'John', 35, 'C#')
Select query returned 1 rows
Name  Age  Language
John  35   C#