Database Access Basics in .NET

This document provides a foundational understanding of how to access and interact with databases using .NET technologies. Effective database management is crucial for building robust and data-driven applications.

Why Database Access Matters

Most applications require storing and retrieving data. Databases serve as the central repository for this information, and .NET offers powerful tools and frameworks to seamlessly integrate with various database systems.

Key Concepts

Data Providers: Libraries that allow .NET applications to connect to specific database systems (e.g., SQL Server, MySQL, PostgreSQL).
Connection Strings: Configuration strings that contain the necessary information to establish a connection to a database, including server name, database name, and authentication details.
Commands: Objects used to execute SQL statements or stored procedures against the database.
Data Readers: Objects that provide a forward-only, read-only stream of data from the database. They are efficient for retrieving large result sets.
Data Sets and Data Tables: In-memory representations of database tables, allowing for offline data manipulation and binding to UI controls.

Core Technologies in .NET for Database Access

ADO.NET

ADO.NET is the foundational data access technology in the .NET Framework and .NET Core/.NET 5+. It provides a set of classes that expose data access services to .NET programmers. ADO.NET is designed to help developers build .NET applications that can access data from various sources, including relational databases, XML data, and other data sources.

Key ADO.NET components include:

SqlConnection, MySqlConnection, NpgsqlConnection, etc. for establishing connections.
SqlCommand, MySqlCommand, etc. for executing commands.
SqlDataReader, MySqlDataReader, etc. for reading data efficiently.
DataSet and DataTable for working with data in memory.

Entity Framework Core (EF Core)

Entity Framework Core is a modern, cross-platform, and extensible version of the popular Microsoft Entity Framework ORM (Object-Relational Mapper). EF Core enables developers to work with a database using .NET objects instead of raw SQL commands, simplifying data access considerably.

With EF Core, you can:

Map .NET classes to database tables (Code-First, Database-First, Model-First approaches).
Perform CRUD (Create, Read, Update, Delete) operations using LINQ queries.
Manage database schema migrations.
Support various database providers.

Note: While ADO.NET offers fine-grained control and efficiency, EF Core provides a higher level of abstraction, making development faster for many common scenarios. The choice often depends on the project's complexity and performance requirements.

A Simple ADO.NET Example (Conceptual)

Here's a conceptual look at how you might connect to a SQL Server database and retrieve data using ADO.NET:


using System;
using System.Data.SqlClient;

public class DatabaseAccessor
{
    public void GetCustomerData(string connectionString)
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            string query = "SELECT CustomerID, CompanyName FROM Customers WHERE City = @City";
            SqlCommand command = new SqlCommand(query, connection);
            command.Parameters.AddWithValue("@City", "London");

            try
            {
                connection.Open();
                SqlDataReader reader = command.ExecuteReader();

                while (reader.Read())
                {
                    Console.WriteLine($"ID: {reader["CustomerID"]}, Name: {reader["CompanyName"]}");
                }
                reader.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error accessing database: {ex.Message}");
            }
        }
    }
}

Next Steps

To delve deeper into database access in .NET, explore the following topics: