创建DataTable

 DataSet ds = new DataSet("mydb");

            DataTable table = new DataTable("mytable");
            table.CaseSensitive = false;
            table.MinimumCapacity = 100;
            table.TableName = "emp";

            DataColumn colEmpno = new DataColumn();
            colEmpno.ColumnName = "empno";
            colEmpno.DataType = typeof(int);
            colEmpno.AutoIncrement = true; //设置自增长
            colEmpno.AutoIncrementSeed = 1000;
            colEmpno.AutoIncrementStep = 1;
            table.Columns.Add(colEmpno);
            table.Columns.Add(new DataColumn("empname", typeof(string)));
            table.Columns.Add(new DataColumn("hiredate", typeof(System.DateTime)));

            DataRow row1 = table.NewRow(); //增加数据
            //row1["empno"] = 1000;
            row1["empname"] = "apq";
            row1["hiredate"] = DateTime.Parse("2009-1-9");
            table.Rows.Add(row1);

            DataRow row2 = table.NewRow(); //增加数据
            //row2["empno"] = 1001;
            row2["empname"] = "bob";
            row2["hiredate"] = DateTime.Parse("2008-5-1");
            table.Rows.Add(row2);

            ds.Tables.Add(table);

            dataGridView1.DataSource = table;

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Configuration;


namespace SqlDataAdapterTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string connStr = ConfigurationManager.ConnectionStrings["sqlconn"].ConnectionString;
            SqlConnection conn = new SqlConnection(connStr);
            conn.Open();

            string sql = "select * from emp";
            SqlDataAdapter adapter = new SqlDataAdapter(sql, conn);
            DataSet ds = new DataSet();
            //adapter.Fill(ds);
            //dataGridView1.DataSource = ds.Tables[0]; //显示数据
            adapter.Fill(ds, "emp"); //给表起个名字
            dataGridView1.DataSource = ds;
            dataGridView1.DataMember = "emp";

            conn.Dispose();
            conn.Close();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            string connStr = ConfigurationManager.ConnectionStrings["sqlconn"].ConnectionString;
            SqlConnection conn = new SqlConnection(connStr);
            conn.Open();

            string sql = "select * from emp";
            SqlDataAdapter adapter = new SqlDataAdapter(sql, conn);
            DataTable table = new DataTable("emp");
            adapter.Fill(table);
            dataGridView1.DataSource = table.DefaultView; //和dataGridView控件绑定数据

            conn.Dispose();
            conn.Close();
        }

        //用DataTable加载SqlDataReader指向的对象
        private void button3_Click(object sender, EventArgs e)
        {
            string connStr = ConfigurationManager.ConnectionStrings["sqlconn"].ConnectionString;
            SqlConnection conn = new SqlConnection(connStr);
            conn.Open();
            string sql = "select * from emp";
            SqlCommand cmd = new SqlCommand(sql, conn);
            SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            DataTable table = new DataTable("emp");
            table.Load(reader);
            dataGridView1.DataSource = table;
            reader.Close();
        }
    }
}