Sql server 实现增删改查

VS2008 C# SQL server

  using System.Data.SqlClient;

 SqlConnection conn;

 //连接数据库
 private void Form1_Load(object sender, EventArgs e)
 {
     string constr = "server=ACER-PC\\LI;database=db_test;uid=sa;pwd=123";
     conn = new SqlConnection(constr);  //数据库连接
 }

 //查看数据库信息

 //这里只要连接数据库即可，不必打开数据库
 private void button1_Click(object sender, EventArgs e)
 {
     SqlCommand cmd = new SqlCommand("select * from tb_ls", conn);

     SqlDataAdapter sda = new SqlDataAdapter();
     sda.SelectCommand = cmd;

     DataSet ds = new DataSet();

     sda.Fill(ds, "cs");

     dataGridView1.DataSource = ds.Tables[0];
 }

 //删除选中的一行信息
 private void button2_Click(object sender, EventArgs e)
 {
     if (this.dataGridView1.SelectedRows.Count > 0)
     {
         DataRowView drv = dataGridView1.SelectedRows[0].DataBoundItem as DataRowView;
         drv.Delete();
     }
     conn.Open();//打开数据库
     SqlCommand cmd = new SqlCommand("delete from tb_ls where 编号="+this.dataGridView1.CurrentRow.Cells["编号"].Value+"",conn);
     cmd.ExecuteNonQuery();
     conn.Close();//关闭数据库
 }

 //添加信息
 private void button3_Click(object sender, EventArgs e)
 {
     conn.Open();
     SqlCommand cmd = new SqlCommand("insert into tb_ls values('"+textBox1.Text+"','"+textBox2.Text+"','"+textBox3.Text+"','"+textBox4.Text+"')",conn);
     cmd.ExecuteNonQuery();
     conn.Close();
 }

 private void button4_Click(object sender, EventArgs e)
 {
     conn.Open();
     SqlCommand cmd = new SqlCommand("update tb_ls set 姓名='"+textBox2.Text+"',性别='"+textBox3.Text+"',年龄='"+textBox4.Text+"' where 编号='"+textBox1.Text+"'",conn);
     textBox1.ReadOnly = false;
     cmd.ExecuteNonQuery();
     conn.Close();
 }

 //将选中的某一行的信息显示在TextBox文本框中
  private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
  {
      textBox1.ReadOnly = true;
      textBox1.Text = this.dataGridView1.CurrentRow.Cells["编号"].Value.ToString();
      textBox2.Text = this.dataGridView1.CurrentRow.Cells["姓名"].Value.ToString();
      textBox3.Text = this.dataGridView1.CurrentRow.Cells["性别"].Value.ToString();
      textBox4.Text = this.dataGridView1.CurrentRow.Cells["年龄"].Value.ToString();
  }