C# drivers

• PostgreSQL Npgsql Driver

Npgsql is an open source ADO.NET Data Provider for PostgreSQL. It allows programs written in C#, Visual Basic, and F# to access YugabyteDB. It is implemented in 100% C# code, and is free and open source.

CRUD operations with PostgreSQL Npgsql driver

Learn how to establish a connection to YugabyteDB database and begin basic CRUD operations using the steps in the Build an application page under the Quick start section.

The following section breaks down the quick start example to demonstrate how to perform common tasks required for C# application development using the Npgsql driver.

After completing these steps, you should have a working C# application that uses the Npgsql driver to connect to your cluster, set up tables, run a query, and print out results.

Step 1: Add the Npgsql driver dependency

If you are using Visual Studio IDE, follow these steps:

1. Open your Project Solution View.
2. Right-click on Packages and click Add Packages.
3. Search for Npgsql and click Add Package.

To add the Npgsql package to your project when not using an IDE, use the following dotnet command:

dotnet add package Npgsql

or any of the other methods mentioned on the nuget page for Npgsql.

Step 2: Connect to your Cluster

After setting up the dependencies, implement a C# client application that uses the Npgsql driver to connect to your YugabyteDB cluster and run a query on the sample data.

Import Npgsql and use the NpgsqlConnection class for getting connection objects for the YugabyteDB database that can be used for performing DDLs and DMLs against the database.

The following is an example URL for connecting to YugabyteDB.

var yburl = "host=localhost;port=5433;database=yb_demo;user id=yugabyte;password="
NpgsqlConnection conn = new NpgsqlConnection(yburl)

Using SSL

The .NET Npgsql driver validates certificates differently from other PostgreSQL drivers. When you specify SSL mode require, the driver verifies the certificate by default (like the verify-ca or verify-full modes), and fails for self-signed certificates (like YugabyteDB's). You can override this by specifying "Trust Server Certificate=true", in which case it bypasses walking the certificate chain to validate trust and hence works like other drivers' require mode. In this case, the Root-CA certificate is not required to be configured.

The following is an example connection string builder for connecting to a YugabyteDB cluster with SSL enabled.

var connStringBuilder = new NpgsqlConnectionStringBuilder();
connStringBuilder.Host = "22420e3a-768b-43da-8dcb-xxxxxx.aws.ybdb.io";
connStringBuilder.Port = 5433;
connStringBuilder.SslMode = SslMode.Require;
connStringBuilder.Username = "admin";
connStringBuilder.Password = "xxxxxx";
connStringBuilder.Database = "yugabyte";
connStringBuilder.TrustServerCertificate = true;
CRUD(connStringBuilder.ConnectionString);

Step 3: Query the YugabyteDB cluster from your application

Next, copy the following sample code to the Program.cs file to set up YugbyteDB tables and query the table contents from the C# client. Ensure you replace the connection string yburl with the credentials of your cluster and SSL certificates if required.

using System;
using Npgsql;

namespace Yugabyte_CSharp_Demo
{
    class Program
    {
        static void Main(string[] args)
        {
            NpgsqlConnection conn = new NpgsqlConnection("host=localhost;port=5433;database=yb_demo;user id=yugabyte;password=");

            try
            {
                conn.Open();

                NpgsqlCommand empCreateCmd = new NpgsqlCommand("CREATE TABLE employee (id int PRIMARY KEY, name varchar, age int, language varchar);", conn);
                empCreateCmd.ExecuteNonQuery();
                Console.WriteLine("Created table Employee");

                NpgsqlCommand empInsertCmd = new NpgsqlCommand("INSERT INTO employee (id, name, age, language) VALUES (1, 'John', 35, 'CSharp');", conn);
                int numRows = empInsertCmd.ExecuteNonQuery();
                Console.WriteLine("Inserted data (1, 'John', 35, 'CSharp')");

                NpgsqlCommand empPrepCmd = new NpgsqlCommand("SELECT name, age, language FROM employee WHERE id = @EmployeeId", conn);
                empPrepCmd.Parameters.Add("@EmployeeId", NpgsqlTypes.NpgsqlDbType.Integer);

                empPrepCmd.Parameters["@EmployeeId"].Value = 1;
                NpgsqlDataReader reader = empPrepCmd.ExecuteReader();

                Console.WriteLine("Query returned:\nName\tAge\tLanguage"); 
                while (reader.Read())
                {
                    Console.WriteLine("{0}\t{1}\t{2}", reader.GetString(0), reader.GetInt32(1), reader.GetString(2));
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Failure: " + ex.Message);
            }
            finally
            {
                if (conn.State != System.Data.ConnectionState.Closed)
                {
                    conn.Close();
                }
            }
        }
    }
}

When you run the project, it should output something like the following:

Created table Employee
Inserted data (1, 'John', 35, 'CSharp')
Query returned:
Name  Age  Language
John  35   CSharp

If you don't get any output, or an error, verify that the connection string in the Program.cs file has the correct parameters.

Next steps

• Learn how to build C# applications using EntityFramework ORM.
• Learn more about the fundamentals of the Npgsql driver.