Question

conn.Open();
string sql = "Update tbl_return set DateReturned = @dreturn,Penalty = @penalty,DaysOverdue=@daysoverdue where ID=@id";
daysoverdue = (dateTimePicker2.Value - dateTimePicker3.Value).Days;

penalty = daysoverdue * fine;
txtfine.Text = penalty.ToString();
txtdoverdue.Text = daysoverdue.ToString();
MySqlCommand sda = new MySqlCommand(sql, conn);

sda.Parameters.AddWithValue("@time", time);
sda.Parameters.AddWithValue("@penalty", penalty);
sda.Parameters.AddWithValue("@daysoverdue", daysoverdue);
sda.Parameters.AddWithValue("@dreturn", datertrnd);
sda.Parameters.AddWithValue("@id", lblid.Text);

sda.ExecuteNonQuery();
conn.Close();

MessageBox.Show("Book has been Returned");

这是我计算过期书的罚款代码。当我在截止日期之前退回书籍时，会产生负数。在预定日期之后归还书籍时，我希望它为0。请帮助我。谢谢！

Answer 1

daysoverdue = (dateTimePicker2.Value - dateTimePicker3.Value).Days;
if(daysoverdue < 0)
   daysoverdue  = 0 

//in this case your penalty will be 0.

使用datetimepicker c＃计算罚款

1 个答案: