ADO.NET: основы работы с базами данных

ADO.NET (ActiveX Data Objects for .NET)

ADO.NET is a technology developed by Microsoft for accessing databases from applications written on the .NET platform. It is part of the core .NET framework and provides a convenient and efficient way to work with data.

ADO.NET was introduced with the release of .NET Framework 1.0 and replaced the older data access technology ADO (ActiveX Data Objects), which was used in COM-based applications. The main goals of ADO.NET were to improve performance and expand functionality for data processing.

At the core of ADO.NET lies a model called "disconnected data model". This means that the application retrieves data from the database and stores it in objects called DataSets. A DataSet is a container that holds tables, columns, rows, and relationships between data. After retrieving the data, the application can work with it without being connected to the database. This allows for high performance and scalability, especially in situations where the network connection between the application and the database is unstable or slow.

ADO.NET supports various data providers that allow connecting to different types of databases, such as Microsoft SQL Server, Oracle, MySQL, and others. Each data provider offers its own classes and methods for working with the database. At the core of all data providers lies a common interface, including IDbConnection, IDbCommand, IDbDataAdapter, IDbDataReader, etc. This allows for using common code to work with databases from different providers.

Here is an example of using ADO.NET to retrieve data from a MySQL database using the MySql.Data data provider:

using System;
using MySql.Data.MySqlClient;

namespace ADO.NET_Example
{
    class Program
    {
        static void Main(string[] args)
        {
            string connectionString = "server=localhost;database=test;uid=root;pwd=12345";

            using (MySqlConnection connection = new MySqlConnection(connectionString))
            {
                string query = "SELECT * FROM users";

                MySqlCommand command = new MySqlCommand(query, connection);

                connection.Open();

                using (MySqlDataReader reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        int id = reader.GetInt32("id");
                        string name = reader.GetString("name");
                        int age = reader.GetInt32("age");

                        Console.WriteLine($"User: ID={id}, Name={name}, Age={age}");
                    }
                }
            }
        }
    }
}
  

In this example, we establish a connection to a MySQL database, execute a query to retrieve data, and display the results on the console. Here, we use the MySql.Data data provider, which provides classes such as MySqlConnection, MySqlCommand, and MySqlDataReader for working with MySQL databases.

ADO.NET provides many other capabilities, such as executing stored procedures, data updates, transactions, and more. It is a powerful tool for working with data in .NET applications and can be used in a wide range of software development scenarios.

In conclusion, ADO.NET is a key technology for accessing data from .NET applications. It provides a convenient and efficient way to work with databases, supports various data providers, and offers a wide range of functionality for data processing. I hope this detailed answer helps you better understand ADO.NET and its capabilities.