数据集和数据适配器示例

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;using System.Data.OleDb;namespace 数据集和数据适配器示例{    public partial class Form1 : Form    {        private OleDbConnection conn;        private OleDbDataAdapter da;        private DataSet ds;        public Form1()        {            InitializeComponent();        }        private void ListBoxFill()        {            if (this.ds.Tables[0].Rows != null) this.ds.Tables[0].Rows.Clear();            this.listBoxEmployee.DataSource = null;            this.listBoxEmployee.Items.Clear();            this.da.Fill(ds, "雇员");            this.listBoxEmployee.DataSource = ds.Tables["雇员"];            this.listBoxEmployee.DisplayMember = "姓名";            this.listBoxEmployee.ValueMember = "雇员ID";        }        private void Form1_Load(object sender, EventArgs e)        {            string connectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Northwind.mdb";            string queryString = "SELECT 雇员ID,姓氏,名字,姓氏+名字 AS 姓名 FROM 雇员";            this.conn = new OleDbConnection(connectionString);            this.ds = new DataSet();            this.ds.Tables.Add("雇员");            this.da = new OleDbDataAdapter(queryString, conn);            //对数据适配器设置插入命令，INSERT语句中包含的问好表示查询参数            this.da.InsertCommand = new OleDbCommand("INSERT INTO 雇员(姓氏,名字) VALUES(?,?)", conn);            this.da.InsertCommand.Parameters.AddWithValue("姓氏", "");            this.da.InsertCommand.Parameters.AddWithValue("名字", "");            //对数据适配器设置更新命令，UPDATE语句中包含的问好表示查询参数            this.da.UpdateCommand = new OleDbCommand("UPDATE 雇员 SET 姓氏=?,名字=? WHERE 雇员ID=?", conn);            this.da.UpdateCommand.Parameters.AddWithValue("姓氏","");            this.da.UpdateCommand.Parameters.AddWithValue("名字","");            this.da.UpdateCommand.Parameters.AddWithValue("雇员ID", -1);            //对数据适配器设置删除命令            this.da.DeleteCommand = new OleDbCommand("DELETE * FROM 雇员 WHERE 雇员ID=?", conn);            this.da.DeleteCommand.Parameters.AddWithValue("雇员ID", -1);            //对雇员姓名信息填充列表框            this.ListBoxFill();        }        private void buttonAdd_Click(object sender, EventArgs e)        {            if (this.textBoxLastName.Text == "" || this.textBoxFirstName.Text == "")            {                this.labelMsg.Text = "姓氏和名字不能为空！！";                return;            }            this.da.InsertCommand.Parameters["姓氏"].Value = this.textBoxLastName.Text;            this.da.InsertCommand.Parameters["名字"].Value = this.textBoxFirstName.Text;            DataRow dr = this.ds.Tables[0].NewRow();            dr["姓氏"] = this.textBoxLastName.Text;            dr["名字"] = this.textBoxFirstName.Text;            this.ds.Tables[0].Rows.Add(dr);            this.da.Update(this.ds, "雇员");            this.ListBoxFill();            this.listBoxEmployee.SelectedIndex = this.listBoxEmployee.Items.Count - 1;            this.labelMsg.Text = "新纪录添加成功！";            this.textBoxLastName.Text = "";            this.textBoxFirstName.Text = "";            this.textBoxLastName.Focus();        }        private void buttonEdit_Click(object sender, EventArgs e)        {            int selectedIndex = this.listBoxEmployee.SelectedIndex;            if (this.textBoxLastName.Text == "" || this.textBoxFirstName.Text == "")            {                this.labelMsg.Text = "姓氏和名字不能为空！！"; return;            }            this.da.UpdateCommand.Parameters["雇员ID"].Value = this.listBoxEmployee.SelectedValue;            this.da.UpdateCommand.Parameters["姓氏"].Value=this.textBoxLastName.Text;            this.da.UpdateCommand.Parameters["名字"].Value=this.textBoxFirstName.Text;            //获取当前选择的数据行            DataRow dr = this.ds.Tables["雇员"].Select("雇员ID=" + this.listBoxEmployee.SelectedValue)[0];            dr["姓氏"] = this.textBoxLastName.Text;            dr["名字"] = this.textBoxFirstName.Text;            this.da.Update(this.ds, "雇员");            this.listBoxEmployee.SelectedIndex = selectedIndex;            this.labelMsg.Text = "选定的记录已被更新。";            this.ListBoxFill();        }        private void buttonDelete_Click(object sender, EventArgs e)        {            this.da.DeleteCommand.Parameters["雇员ID"].Value = this.listBoxEmployee.SelectedValue;            DataRow dr = this.ds.Tables[0].Select("雇员ID=" + this.listBoxEmployee.SelectedValue)[0];            dr.Delete();            this.da.Update(this.ds, "雇员");            this.ListBoxFill();            this.labelMsg.Text = "选定的记录已被删除";        }        private void buttonExit_Click(object sender, EventArgs e)        {            Application.Exit();        }        private void listBoxEmployee_Click(object sender, EventArgs e)        {            DataRow dr = null;            if (this.listBoxEmployee.SelectedIndex != -1)            {                dr = this.ds.Tables[0].Select("雇员ID=" + this.listBoxEmployee.SelectedValue)[0];                this.textBoxLastName.Text = dr["姓氏"].ToString();                this.textBoxFirstName.Text = dr["名字"].ToString();            }        }    }}