c#中DataGridView实现多选删除

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.bind();
        }
        public void bind()
        {
            string sql = "select * from titles";
            this.dataGridView1.DataSource = dal.dao.getTable(sql);
        }
        private void button1_Click(object sender, EventArgs e)
        {
            string xzid = "";
            for (int i = 0; i < dataGridView1.Rows.Count; i++)
            {
                DataGridViewRow row = dataGridView1.Rows[i];

                if (row.Cells[0].Value != null)
                {
                    if (bool.Parse(row.Cells[0].Value.ToString()) == true)
                    {
                        int row1 = row.Index;

                        xzid =xzid+"'"+ this.dataGridView1[1, row1].Value.ToString() +"'"+",";

                    }
                }
               
            }
            if (xzid.Length > 0)
            {
                xzid = xzid.Substring(0, xzid.Length - 1);
                //MessageBox.Show(xzid);
            }

            string sql1 = string.Format("delete from titles where title_id in ({0})", xzid);
            if (MessageBox.Show("确实要删除选中的行吗？   注意：删除后就无法恢复了！", "警告",
                MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
            {
                int g = dal.dao.InsertOne(sql1);
                if (g > 0)
                {
                    MessageBox.Show("删除成功~~");
                }
                else
                    MessageBox.Show("删除失败!!!");
            }
            else
                return;

            bind();
        }


    }