To read data from a PostgreSQL database using .NET, you can use the Npgsql library, which is a .NET data provider for PostgreSQL. Here’s an example code
using System; using Npgsql; class Program { static void Main() { // Connection string for the PostgreSQL database string connString = "Host=your_host;Username=your_user;Password=your_password;Database=your_database"; // Create a new PostgreSQL connection using (NpgsqlConnection conn = new NpgsqlConnection(connString)) { conn.Open(); // SQL query to retrieve data string query = "SELECT * FROM your_table"; // Create a command object with the query and connection using (NpgsqlCommand cmd = new NpgsqlCommand(query, conn)) { // Execute the query and obtain a data reader using (NpgsqlDataReader reader = cmd.ExecuteReader()) { // Iterate over the rows and print the values while (reader.Read()) { // Access columns by their names or indexes string name = reader.GetString("name"); int age = reader.GetInt32("age"); string email = reader.GetString("email"); Console.WriteLine($"Name: {name}, Age: {age}, Email: {email}"); } } } } } }
In this example, replace 'your_host', 'your_user', 'your_password', and 'your_database' with the actual connection details for your PostgreSQL database.
The code establishes a connection to the PostgreSQL database using the specified host, username, password, and database name. It then creates a command object with the SQL query and the connection.
The example executes the query using ExecuteReader() to obtain a data reader. It then iterates over the rows in the result set using Read(), and retrieves the values from each row using column names or indexes.
Finally, the connection, command, and reader objects are disposed to release the resources.
Make sure to have the Npgsql library installed in your .NET project. You can install it via NuGet Package Manager or through the .NET CLI:
dotnet add package Npgsql
Remember to handle any exceptions that may occur during the database connection or query execution for proper error handling.