Quickstart: Use .NET (C#) to connect and query data in Azure Database for PostgreSQL - Flexible Server

Article
07/12/2024

APPLIES TO: Azure Database for PostgreSQL - Flexible Server

This quickstart demonstrates how to connect to an Azure Database for PostgreSQL flexible server instance using a C# application. It shows how to use SQL statements to query, insert, update, and delete data in the database. The steps in this article assume that you are familiar with developing using C#, and that you are new to working with Azure Database for PostgreSQL flexible server.

Prerequisites

For this quickstart you need:

An Azure account with an active subscription. Create an account for trial.
Create an Azure Database for PostgreSQL flexible server instance using Azure portal
or Azure CLI if you do not have one.
Use the empty postgres database available on the server or create a new database.
Install the .NET SDK for your platform (Windows, Ubuntu Linux, or macOS) for your platform.
Install Visual Studio to build your project.
Install Npgsql NuGet package in Visual Studio.

Get connection information

Get the connection information needed to connect to the Azure Database for PostgreSQL flexible server instance. You need the fully qualified server name and login credentials.

Log in to the Azure portal.
From the left-hand menu in Azure portal, click All resources, and then search for the server you have created (such as mydemoserver).
Click the server name.
From the server's Overview panel, make a note of the Server name and Server admin login name. If you forget your password, you can also reset the password from this panel.

Step 1: Connect and insert data

Use the following code to connect and load the data using CREATE TABLE and INSERT INTO SQL statements. The code uses NpgsqlCommand class with method:

Open() to establish a connection to the Azure Database for PostgreSQL flexible server database.
CreateCommand() sets the CommandText property.
ExecuteNonQuery() method to run the database commands.

Important

Replace the Host, DBName, User, and Password parameters with the values that you specified when you created the server and database.

using System;
using Npgsql;

namespace Driver
{
    public class AzurePostgresCreate
    {
        // Obtain connection string information from the portal
        //
        private static string Host = "mydemoserver.postgres.database.chinacloudapi.cn";
        private static string User = "mylogin";
        private static string  DBname = "postgres";
        private static string Password = "<server_admin_password>";
        private static string Port = "5432";

        static void Main(string[] args)
        {
            // Build connection string using parameters from portal
            //
            string connString =
                String.Format(
                    "Server={0};Username={1};Database={2};Port={3};Password={4};SSLMode=Prefer",
                    Host,
                    User,
                    DBname,
                    Port,
                    Password);


            using (var conn = new NpgsqlConnection(connString))

            {
                Console.Out.WriteLine("Opening connection");
                conn.Open();

                using (var command = new NpgsqlCommand("DROP TABLE IF EXISTS inventory", conn))
                {
                    command.ExecuteNonQuery();
                    Console.Out.WriteLine("Finished dropping table (if existed)");

                }

                using (var command = new NpgsqlCommand("CREATE TABLE inventory(id serial PRIMARY KEY, name VARCHAR(50), quantity INTEGER)", conn))
                {
                    command.ExecuteNonQuery();
                    Console.Out.WriteLine("Finished creating table");
                }

                using (var command = new NpgsqlCommand("INSERT INTO inventory (name, quantity) VALUES (@n1, @q1), (@n2, @q2), (@n3, @q3)", conn))
                {
                    command.Parameters.AddWithValue("n1", "banana");
                    command.Parameters.AddWithValue("q1", 150);
                    command.Parameters.AddWithValue("n2", "orange");
                    command.Parameters.AddWithValue("q2", 154);
                    command.Parameters.AddWithValue("n3", "apple");
                    command.Parameters.AddWithValue("q3", 100);

                    int nRows = command.ExecuteNonQuery();
                    Console.Out.WriteLine(String.Format("Number of rows inserted={0}", nRows));
                }
            }

            Console.WriteLine("Press RETURN to exit");
            Console.ReadLine();
        }
    }
}

Step 2: Read data

Use the following code to connect and read the data using a SELECT SQL statement. The code uses NpgsqlCommand class with method:

Open() to establish a connection to PostgreSQL.
CreateCommand() and ExecuteReader() to run the database commands.
Read() to advance to the record in the results.
GetInt32() and GetString() to parse the values in the record.

Important

Replace the Host, DBName, User, and Password parameters with the values that you specified when you created the server and database.

using System;
using Npgsql;

namespace Driver
{
    public class AzurePostgresRead
    {
        // Obtain connection string information from the portal
        //
        private static string Host = "mydemoserver.postgres.database.chinacloudapi.cn";
        private static string User = "mylogin";
        private static string  DBname = "postgres";
        private static string Password = "<server_admin_password>";
        private static string Port = "5432";

        static void Main(string[] args)
        {
            // Build connection string using parameters from portal
            //
            string connString =
                String.Format(
                    "Server={0}; User Id={1}; Database={2}; Port={3}; Password={4};SSLMode=Prefer",
                    Host,
                    User,
                    DBname,
                    Port,
                    Password);

            using (var conn = new NpgsqlConnection(connString))
            {

                Console.Out.WriteLine("Opening connection");
                conn.Open();


                using (var command = new NpgsqlCommand("SELECT * FROM inventory", conn))
                {

                    var reader = command.ExecuteReader();
                    while (reader.Read())
                    {
                        Console.WriteLine(
                            string.Format(
                                "Reading from table=({0}, {1}, {2})",
                                reader.GetInt32(0).ToString(),
                                reader.GetString(1),
                                reader.GetInt32(2).ToString()
                                )
                            );
                    }
                    reader.Close();
                }
            }

            Console.WriteLine("Press RETURN to exit");
            Console.ReadLine();
        }
    }
}

Step 3: Update data

Use the following code to connect and update the data using an UPDATE SQL statement. The code uses NpgsqlCommand class with method:

Open() to establish a connection to Azure Database for PostgreSQL flexible server.
CreateCommand(), sets the CommandText property.
ExecuteNonQuery() method to run the database commands.

Important

Replace the Host, DBName, User, and Password parameters with the values that you specified when you created the server and database.

using System;
using Npgsql;

namespace Driver
{
    public class AzurePostgresUpdate
    {
        // Obtain connection string information from the portal
        //
        private static string Host = "mydemoserver.postgres.database.chinacloudapi.cn";
        private static string User = "mylogin";
        private static string  DBname = "postgres";
        private static string Password = "<server_admin_password>";
        private static string Port = "5432";

        static void Main(string[] args)
        {
            // Build connection string using parameters from portal
            //
            string connString =
                String.Format(
                    "Server={0}; User Id={1}; Database={2}; Port={3}; Password={4};SSLMode=Prefer",
                    Host,
                    User,
                    DBname,
                    Port,
                    Password);

            using (var conn = new NpgsqlConnection(connString))
            {

                Console.Out.WriteLine("Opening connection");
                conn.Open();

                using (var command = new NpgsqlCommand("UPDATE inventory SET quantity = @q WHERE name = @n", conn))
                {
                    command.Parameters.AddWithValue("n", "banana");
                    command.Parameters.AddWithValue("q", 200);
                    int nRows = command.ExecuteNonQuery();
                    Console.Out.WriteLine(String.Format("Number of rows updated={0}", nRows));
                }
            }

            Console.WriteLine("Press RETURN to exit");
            Console.ReadLine();
        }
    }
}

Step 4: Delete data

Use the following code to connect and delete data using a DELETE SQL statement.

The code uses NpgsqlCommand class with method Open() to establish a connection to the Azure Database for PostgreSQL flexible server database. Then, the code uses the CreateCommand() method, sets the CommandText property, and calls the method ExecuteNonQuery() to run the database commands.

Important

Replace the Host, DBName, User, and Password parameters with the values that you specified when you created the server and database.

using System;
using Npgsql;

namespace Driver
{
    public class AzurePostgresDelete
    {
        // Obtain connection string information from the portal
        //
        private static string Host = "mydemoserver.postgres.database.chinacloudapi.cn";
        private static string User = "mylogin@mydemoserver";
        private static string  DBname = "postgres";
        private static string Password = "<server_admin_password>";
        private static string Port = "5432";

        static void Main(string[] args)
        {
            // Build connection string using parameters from portal
            //
            string connString =
                String.Format(
                    "Server={0}; User Id={1}; Database={2}; Port={3}; Password={4};SSLMode=Prefer",
                    Host,
                    User,
                    DBname,
                    Port,
                    Password);

            using (var conn = new NpgsqlConnection(connString))
            {
                Console.Out.WriteLine("Opening connection");
                conn.Open();

                using (var command = new NpgsqlCommand("DELETE FROM inventory WHERE name = @n", conn))
                {
                    command.Parameters.AddWithValue("n", "orange");

                    int nRows = command.ExecuteNonQuery();
                    Console.Out.WriteLine(String.Format("Number of rows deleted={0}", nRows));
                }
            }

            Console.WriteLine("Press RETURN to exit");
            Console.ReadLine();
        }
    }
}

Clean up resources

To clean up all resources used during this quickstart, delete the resource group using the following command:

az group delete \
    --name $AZ_RESOURCE_GROUP \
    --yes

Next steps

Manage Azure Database for PostgreSQL server using Portal

Manage Azure Database for PostgreSQL server using CLI

Quickstart: Use .NET (C#) to connect and query data in Azure Database for PostgreSQL - Flexible Server

Prerequisites

Get connection information

Step 1: Connect and insert data

Step 2: Read data

Step 3: Update data

Step 4: Delete data

Clean up resources

Next steps

Additional resources