C# datagridview如何实现多行增删改查？

datagridview插入多行到数据库:

private void button3_Click(object sender, EventArgs e)
{
openObj();
try
{
string sTrSql = string.Empty;
for (int i = 0; i < dataGridView1.Rows.Count; i++)
{
sTrSql += "insert into demo (demo_id,demo_name,demo_indent,demo_count,demo_create) values('" + dataGridView1.Rows[i].Cells[0].Value + "','" + dataGridView1.Rows[i].Cells[1].Value + "','" + dataGridView1.Rows[i].Cells[2].Value + "','" + dataGridView1.Rows[i].Cells[3].Value + "','" + dataGridView1.Rows[i].Cells[4].Value + "')";
}
using (com = new SqlCommand(sTrSql, con))
{
if (com.ExecuteNonQuery() != -1)
{
MessageBox.Show("添加成功");
}
}
}
catch (Exception ex)
{
MessageBox.Show("添加失败,详细信息：" + ex.ToString());
}
closeObj();