我的问题是:我想通过总结两个日期之间的货币类型列来写结果。
代码:
using (NpgsqlConnection b = new NpgsqlConnection("Server=127.0.0.1;Port=5432;User Id=postgres;Password=xxxxxxxx;DataBase=deneme;"))
{
try
{
b.Open();
NpgsqlCommand c = new NpgsqlCommand("SELECT SUM(tutar) FROM market where tarih between '" + dateTimePicker1.Value + "' and '" + dateTimePicker2.Value + "'", b);
double toplam = ((double)c.ExecuteScalar());
b.Close();
b.Dispose();
MessageBox.Show(toplam.ToString("n"));
}