form_deleteitem.cs

本人的总结

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Data.SqlClient;

namespace 数据库更新
{
	/// <summary>
	/// Form_DeleteItem 的摘要说明。
	/// </summary>
	public class Form_DeleteItem : System.Windows.Forms.Form
	{
		private System.Windows.Forms.Label label1;
		private System.Windows.Forms.Button button3;
		private System.Windows.Forms.Button button2;
		private System.Windows.Forms.Button button1;
		private System.Windows.Forms.ComboBox comboBox1;
		private System.Windows.Forms.Label label2;
		private System.Windows.Forms.Button button4;
		/// <summary>
		/// 必需的设计器变量。
		/// </summary>
		private System.ComponentModel.Container components = null;

		public Form_DeleteItem()
		{
			//
			// Windows 窗体设计器支持所必需的
			//
			InitializeComponent();

			//
			// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
			//
			SqlConnection connection = new SqlConnection();
			SqlCommand command = new SqlCommand();

			connection.ConnectionString = "workstation id=localhost;packet size=4096;integrated security=SSPI;initial catalog=Northwind;persist security info=False";
			command.CommandText = "SELECT * FROM Categories";
			command.Connection = connection;
			connection.Open();
			SqlDataReader reader = command.ExecuteReader();
			while(reader.Read())
			{
				this.comboBox1.Items.Add(reader[0].ToString());
			}
			connection.Close();
		}

		/// <summary>
		/// 清理所有正在使用的资源。
		/// </summary>
		protected override void Dispose( bool disposing )
		{
			if( disposing )
			{
				if(components != null)
				{
					components.Dispose();
				}
			}
			base.Dispose( disposing );
		}

		#region Windows 窗体设计器生成的代码
		/// <summary>
		/// 设计器支持所需的方法 - 不要使用代码编辑器修改
		/// 此方法的内容。
		/// </summary>
		private void InitializeComponent()
		{
			this.label1 = new System.Windows.Forms.Label();
			this.button3 = new System.Windows.Forms.Button();
			this.button2 = new System.Windows.Forms.Button();
			this.button1 = new System.Windows.Forms.Button();
			this.comboBox1 = new System.Windows.Forms.ComboBox();
			this.label2 = new System.Windows.Forms.Label();
			this.button4 = new System.Windows.Forms.Button();
			this.SuspendLayout();
			// 
			// label1
			// 
			this.label1.Font = new System.Drawing.Font("宋体", 10.5F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((System.Byte)(134)));
			this.label1.Location = new System.Drawing.Point(36, 16);
			this.label1.Name = "label1";
			this.label1.Size = new System.Drawing.Size(216, 23);
			this.label1.TabIndex = 17;
			this.label1.Text = "删除数据库中的一个记录";
			this.label1.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
			// 
			// button3
			// 
			this.button3.Location = new System.Drawing.Point(34, 200);
			this.button3.Name = "button3";
			this.button3.Size = new System.Drawing.Size(224, 23);
			this.button3.TabIndex = 16;
			this.button3.Text = "利用数据集更新数据库（工具箱控件）";
			this.button3.Click += new System.EventHandler(this.button3_Click);
			// 
			// button2
			// 
			this.button2.Location = new System.Drawing.Point(34, 168);
			this.button2.Name = "button2";
			this.button2.Size = new System.Drawing.Size(224, 23);
			this.button2.TabIndex = 15;
			this.button2.Text = "利用数据集更新数据库（手工代码）";
			this.button2.Click += new System.EventHandler(this.button2_Click);
			// 
			// button1
			// 
			this.button1.Location = new System.Drawing.Point(34, 136);
			this.button1.Name = "button1";
			this.button1.Size = new System.Drawing.Size(224, 23);
			this.button1.TabIndex = 14;
			this.button1.Text = "利用SQL语句更新数据库";
			this.button1.Click += new System.EventHandler(this.button1_Click);
			// 
			// comboBox1
			// 
			this.comboBox1.Location = new System.Drawing.Point(80, 96);
			this.comboBox1.Name = "comboBox1";
			this.comboBox1.Size = new System.Drawing.Size(121, 20);
			this.comboBox1.TabIndex = 18;
			// 
			// label2
			// 
			this.label2.Location = new System.Drawing.Point(32, 72);
			this.label2.Name = "label2";
			this.label2.Size = new System.Drawing.Size(224, 23);
			this.label2.TabIndex = 19;
			this.label2.Text = "选择要删除的记录的ID号";
			this.label2.TextAlign = System.Drawing.ContentAlignment.MiddleCenter;
			// 
			// button4
			// 
			this.button4.Location = new System.Drawing.Point(112, 232);
			this.button4.Name = "button4";
			this.button4.TabIndex = 20;
			this.button4.Text = "返回";
			this.button4.Click += new System.EventHandler(this.button4_Click);
			// 
			// Form_DeleteItem
			// 
			this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
			this.ClientSize = new System.Drawing.Size(292, 262);
			this.Controls.Add(this.button4);
			this.Controls.Add(this.label2);
			this.Controls.Add(this.comboBox1);
			this.Controls.Add(this.label1);
			this.Controls.Add(this.button3);
			this.Controls.Add(this.button2);
			this.Controls.Add(this.button1);
			this.Name = "Form_DeleteItem";
			this.Text = "Form_DeleteItem";
			this.ResumeLayout(false);

		}
		#endregion

		private void button1_Click(object sender, System.EventArgs e)
		{
			SqlConnection connection = new SqlConnection();
			SqlCommand command = new SqlCommand();

			connection.ConnectionString = "workstation id=localhost;packet size=4096;integrated security=SSPI;initial catalog=Northwind;persist security info=False";
			command.Connection = connection;
			if(this.comboBox1.SelectedIndex != -1)
			{
				connection.Open();
				command.CommandText = "DELETE FROM Categories  WHERE CategoryID=" + this.comboBox1.SelectedItem.ToString();
				try
				{
					command.ExecuteNonQuery();
					MessageBox.Show("数据库记录删除成功","删除记录");
				}
				catch(SqlException x)
				{
					MessageBox.Show("数据库记录删除失败","删除记录");
				}
				connection.Close();
			}
			else
			{
				MessageBox.Show("请选择要删除的记录的ID号","删除记录");
			}

			//将列表框中记录的ID号刷新，去掉已经删掉的记录
			this.comboBox1.SelectedIndex = -1;
			this.comboBox1.Items.Clear();
			SqlCommand command1 = new SqlCommand();

			command1.CommandText = "SELECT * FROM Categories";
			command1.Connection = connection;
			connection.Open();
			SqlDataReader reader = command1.ExecuteReader();
			while(reader.Read())
			{
				this.comboBox1.Items.Add(reader[0].ToString());
			}
			connection.Close();
		}

		private void button2_Click(object sender, System.EventArgs e)
		{
			SqlDataAdapter adapter = new SqlDataAdapter();
			SqlConnection connection = new SqlConnection();
			SqlCommand command = new SqlCommand();
			DataSet ds = new DataSet();
			DataTable table = new DataTable();
			SqlCommandBuilder scb = new SqlCommandBuilder(adapter);

			connection.ConnectionString = "workstation id=localhost;packet size=4096;integrated security=SSPI;initial catalog=Northwind;persist security info=False";
			command.CommandText = "SELECT * FROM Categories WHERE CategoryID=" + this.comboBox1.SelectedItem.ToString();
			command.Connection = connection;
			connection.Open();

			adapter.SelectCommand = command;
			adapter.Fill(ds,"Categories");
			table = ds.Tables["Categories"];


			DataRow row = table.Rows[0];
			table.Rows[0].Delete();

			try
			{
				adapter.Update(ds,"Categories");
				MessageBox.Show("数据库记录删除成功","删除记录");
			}
			catch(SqlException x)
			{
				MessageBox.Show("数据库记录删除失败","删除记录");
			}
			connection.Close();


			//将列表框中记录的ID号刷新，去掉已经删掉的记录
			this.comboBox1.SelectedIndex = -1;
			this.comboBox1.Items.Clear();
			SqlCommand command1 = new SqlCommand();

			command1.CommandText = "SELECT * FROM Categories";
			command1.Connection = connection;
			connection.Open();
			SqlDataReader reader = command1.ExecuteReader();
			while(reader.Read())
			{
				this.comboBox1.Items.Add(reader[0].ToString());
			}
			connection.Close();
		}

		private void button4_Click(object sender, System.EventArgs e)
		{
			new Form1().Show();
			this.Dispose();
		}

		private void button3_Click(object sender, System.EventArgs e)
		{
		
		}
	}
}