conn = SqlConnection(str);
sda.SelectCommand = new SqlCommand("select * from gooduse_tb", conn);
table.Rows[0]["姓名"] = textBox2.Text.Trim();
table.Rows[0]["年龄"] = textBox3.Text.Trim(); ;
scb = new SqlCommandBuilder(sda);
sda.Update(table);
conn.Close();
MessageBox.Show("修改成功!");