我想将datagridview中的多行数据添加到SQL数据库中，但是总是显示“添加失败”，而且添加后查看数据库，只有最后一行数据库加进去了。
求解答，我的头快秃了......(ㄒoㄒ)
我们没有学过多行数据的，我只会单行添加，在网上找了很多资料也没有办法。
上学期我们老师讲的C#简直就是一坨shit，全靠自学，现在又来布置作业，枯了

dim_2是我的数据表

private void 保存转换后坐标ToolStripMenuItem_Click(object sender, EventArgs e)
{
//连接数据库
string connStr = @"Data Source=8RLL4E2HQZ2PO3V;Initial Catalog=Internship;Integrated Security=True";

SqlConnection conn = new SqlConnection();
conn.ConnectionString = connStr;
conn.Open();
//创建SQL命令
SqlCommand cmd = new SqlCommand();
for (int i = 0; i < Pnum; i++)
{
string sql = "insert into dim_2 values(" + this.dataGridView2.Rows[i].Cells[0].Value.ToString() + "," +
this.dataGridView2.Rows[i].Cells[1].Value + "," + this.dataGridView2.Rows[i].Cells[2].Value + "," +
this.dataGridView2.Rows[i].Cells[3].Value + "," + this.dataGridView2.Rows[i].Cells[4].Value + "," +
this.dataGridView2.Rows[i].Cells[5].Value + "," + this.dataGridView2.Rows[i].Cells[6].Value + ")";
cmd.CommandText = sql;
cmd.Connection = conn;
}

int row = cmd.ExecuteNonQuery();

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

if (row == 3)
MessageBox.Show("添加成功！");

else
MessageBox.Show("添加失败!");

}