Connect an application

YSQL
YCQL

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

CRUD operations

The following sections demonstrate how to perform common tasks required for C# application development.

To start building your application, make sure you have met the prerequisites.

Step 1: Add the Npgsql driver dependency

If you are using Visual Studio, add the Npgsql package to your project as follows:

Right-click Dependencies and choose Manage Nuget Packages.
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: Set up the database connection

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 table describes the connection parameters required to connect to the YugabyteDB database.

Parameter	Description	Default
Host	Host name of the YugabyteDB instance	localhost
Port	Listen port for YSQL	5433
Database	Database name	yugabyte
Username	User connecting to the database	yugabyte
Password	Password for the user	yugabyte

The following is a basic example connection string for connecting to YugabyteDB.

var connStringBuilder = "Host=localhost;Port=5433;Database=yugabyte;Username=yugabyte;Password=password"
NpgsqlConnection conn = new NpgsqlConnection(connStringBuilder)

Use SSL

Set up the driver properties to configure the credentials and SSL certificates for connecting to your cluster. The following table describes the additional parameters the .NET Npgsql driver requires as part of the connection string when using SSL.

Npgsql Parameter	Description
SslMode	SSL Mode
RootCertificate	Path to the root certificate on your computer

The following is an example connection string for connecting to YugabyteDB using SSL.

var connStringBuilder = new NpgsqlConnectionStringBuilder();
    connStringBuilder.Host = "22420e3a-768b-43da-8dcb-xxxxxx.aws.yugabyte.cloud";
    connStringBuilder.Port = 5433;
    connStringBuilder.SslMode = SslMode.VerifyFull;
    connStringBuilder.RootCertificate = "/root.crt"; //Provide full path to your root CA.
    connStringBuilder.Username = "admin";
    connStringBuilder.Password = "xxxxxx";
    connStringBuilder.Database = "yugabyte";
    CRUD(connStringBuilder.ConnectionString);

YugabyteDB Aeon clusters require SSL. Refer to Connect applications for instructions on how to obtain the cluster connection parameters and download the CA certificate.

Refer to Configure SSL/TLS for more information on Npgsql default and supported SSL modes, and examples for setting up your connection strings when using SSL.

Step 3: Write your application

Copy the following code to the Program.cs file to set up YugbyteDB tables and query the table contents from the C# client. Replace the connection string connStringBuilder with the credentials of your cluster, and SSL certificates if required.

Warning

On every new connection, the Npgsql driver also makes extra system table queries to map types, which adds significant overhead. It is recommended that you turn this behavior off to significantly reduce connection open execution time.

Set the following option in your connection string builder:

connStringBuilder.ServerCompatibilityMode = ServerCompatibilityMode.NoTypeLoading;

Alternatively, you can add the following to your connection string:

Server Compatibility Mode=NoTypeLoading;

using System;
using Npgsql;

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

            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();
                }
            }
        }
    }
}

You should see output similar to the following:

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

Step 4: Write your application with SSL (optional)

Copy the following code to your Program.cs file , and replace the values in the connStringBuilder object as appropriate for your cluster if you're using SSL.

using System;
using Npgsql;

namespace Yugabyte_CSharp_Demo
{
   class Program
   {
       static void Main(string[] args)
       {
          var connStringBuilder = new NpgsqlConnectionStringBuilder();
           connStringBuilder.Host = "22420e3a-768b-43da-8dcb-xxxxxx.aws.yugabyte.cloud";
           connStringBuilder.Port = 5433;
           connStringBuilder.SslMode = SslMode.VerifyFull;
           connStringBuilder.RootCertificate = "/root.crt" //Provide full path to your root CA.
           connStringBuilder.Username = "admin";
           connStringBuilder.Password = "xxxxxx";
           connStringBuilder.Database = "yugabyte";
           CRUD(connStringBuilder.ConnectionString);
       }
       static void CRUD(string connString)
       {
            NpgsqlConnection conn = new NpgsqlConnection(connString);
           try
           {
               conn.Open();

               NpgsqlCommand empDropCmd = new NpgsqlCommand("DROP TABLE if exists employee;", conn);
               empDropCmd.ExecuteNonQuery();
               Console.WriteLine("Dropped table Employee");

               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 + SSL')");

               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();
               }
           }
       }
   }
}

Run the application

To run the project Program.cs in Visual Studio Code, from the Run menu, choose Start Without Debugging. If you aren't using an IDE, enter the following command:

dotnet run

You should see output similar to the following if you're using SSL:

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

If you receive no output or an error, check the parameters in the connection string.