如题

string sql="select col1 from table"; //col1为你要相加的列
...
using(实例reader)
{
  int sum=0;
  while(reader.Read())
  {
   sum+=reader.GetInt32(0);
  }
}
...
this.TextBoxID.Text=sum.ToString();

SqlConnection conn = new SqlConnection();
        conn.ConnectionString = "Data Source=RGYJ-AVTYN682XD;Initial Catalog=库;User ID=sa;Password=sa123456789";
        SqlCommand Cmd = new SqlCommand();
         = "select 总价 from 库存";
        Cmd.Connection = conn;
        conn.Open();
        float sum = 0;
        SqlDataReader reader = Cmd.ExecuteReader();
        while (reader.Read())
        {
            sum += reader.GetFloat(0);
        }
        this.TextBox2.Text = sum.ToString();
        conn.Close();
        conn.Dispose();
运行后sum += reader.GetFloat(0); 提示转换错误

[ 本帖最后由 yxhrgyj 于 2012-3-26 13:17 编辑 ]

运行后sum += reader.GetFloat(0); 提示转换错误
sum是int类型,而获得的数据是float类型的,float的级别高于int,所以会出现类型转换错误,你把sum定义为float类型就可以了