VS2008C#Sqlserver2008数据库的连接，增删改查

     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();
        }