Библиотека программиста

Все, что необходимо начинающему и опытному программисту

Практический пример на чтение данных из базы данных.

Данный пример показывает принцип чтения данных из базы данных. Программа отображает в сетку содержимое таблицы. В примере используется параметр для фильтрования полученных данных. Код примера:

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
// Пространство для классов Ole
using System.Data.OleDb;
namespace Params
{
	/// 

	/// Summary description for Form1.
	/// 
	public class Form1 : System.Windows.Forms.Form
	{
		// Переменная для сетки
		private System.Windows.Forms.DataGrid dataGrid1;
		private System.Windows.Forms.Button button2;
		private System.Windows.Forms.Label label1;
		private System.Windows.Forms.Button button1;
		/// 

		/// Required designer variable.
		/// 
		private System.ComponentModel.Container components = null;

		public Form1()
		{
			//
			// Required for Windows Form Designer support
			//
			InitializeComponent();

			//
			// TODO: Add any constructor code after InitializeComponent call
			//
		}

		/// 

		/// Clean up any resources being used.
		/// 
		protected override void Dispose( bool disposing )
		{
			if( disposing )
			{
				if (components != null) 
				{
					components.Dispose();
				}
			}
			base.Dispose( disposing );
		}

		#region Windows Form Designer generated code
		/// 

		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// 
		private void InitializeComponent()
		{
			this.dataGrid1 = new System.Windows.Forms.DataGrid();
			this.button2 = new System.Windows.Forms.Button();
			this.label1 = new System.Windows.Forms.Label();
			this.button1 = new System.Windows.Forms.Button();
			((System.ComponentModel.ISupportInitialize)(this.dataGrid1)).BeginInit();
			this.SuspendLayout();
			// 
			// dataGrid1
			// 
			this.dataGrid1.DataMember = "";
			this.dataGrid1.HeaderForeColor = System.Drawing.SystemColors.ControlText;
			this.dataGrid1.Location = new System.Drawing.Point(16, 64);
			this.dataGrid1.Name = "dataGrid1";
			this.dataGrid1.Size = new System.Drawing.Size(576, 384);
			this.dataGrid1.TabIndex = 0;
			// 
			// button2
			// 
			this.button2.Location = new System.Drawing.Point(632, 64);
			this.button2.Name = "button2";
			this.button2.TabIndex = 1;
			this.button2.Text = "Заполнить";
			this.button2.Click += new System.EventHandler(this.button2_Click);
			// 
			// label1
			// 
			this.label1.Location = new System.Drawing.Point(16, 8);
			this.label1.Name = "label1";
			this.label1.TabIndex = 2;
			this.label1.Text = "Данные";
			// 
			// button1
			// 
			this.button1.Location = new System.Drawing.Point(632, 120);
			this.button1.Name = "button1";
			this.button1.TabIndex = 3;
			this.button1.Text = "Параметры";
			this.button1.Click += new System.EventHandler(this.button1_Click);
			// 
			// Form1
			// 
			this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
			this.ClientSize = new System.Drawing.Size(712, 462);
			this.Controls.Add(this.button1);
			this.Controls.Add(this.label1);
			this.Controls.Add(this.dataGrid1);
			this.Controls.Add(this.button2);
			this.Name = "Form1";
			this.Text = "ADO.NET";
			((System.ComponentModel.ISupportInitialize)(this.dataGrid1)).EndInit();
			this.ResumeLayout(false);

		}
		#endregion

		/// 

		/// The main entry point for the application.
		/// 
		
		static void Main() 
		{
			Application.Run(new Form1());
		}

		private void button2_Click(object sender, System.EventArgs e)
		{
			try
			{			
				// Присоединение к базе данных
				OleDbConnection connect = new  OleDbConnection();		
				// Строка соединения с Ole -  провайдером
				connect.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;data  
source=c:\sample.mdb";
				connect.Open();
				OleDbCommand command = new OleDbCommand();
				// Запрос
				command.CommandText = "select * from people";
				command.Connection = connect;
				OleDbDataAdapter adapter = new OleDbDataAdapter(command);
				DataSet dataset = new DataSet();
				// Заполнение сетки
				adapter.Fill(dataset,"People");
				dataGrid1.DataSource = dataset.Tables["People"];

			}
			catch(Exception ex)
			{
				MessageBox.Show(ex.Message);
			}
		}

		private void button1_Click(object sender, System.EventArgs e)
		{
			try
			{
				OleDbConnection connect = new  OleDbConnection();		
				connect.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;data  
source=c:\sample.mdb";
				connect.Open();

				OleDbCommand command = new OleDbCommand();
				// Запрос с параметром	
				command.CommandText = "select * from people where name = ?";
				command.Connection = connect;
				
				OleDbDataAdapter adapter = new OleDbDataAdapter(command);
				// Добавление значения для параметра
				adapter.SelectCommand.Parameters.Add("@name", OleDbType.VarChar, 80).Value = "Oleg";
				

				DataSet dataset = new DataSet();
				adapter.Fill(dataset,"People");
				dataGrid1.DataSource = dataset.Tables["People"];

			}
			catch(Exception ex)
			{
				MessageBox.Show(ex.Message);
			}
		}
	}
}

<< Назад         В начало         Далее >>

Библиотека программиста. 2009.
Администратор: admin@programmer-lib.ru