如果条件为true，则中断或关闭sqlDatareader并退出使用（SqlDataReader rdr = cmd.ExecuteReader（））方法

Question

using (SqlDataReader rdr = cmd.ExecuteReader())
{
    while(rdr.Read())
    {
        DateTime dt2 = Convert.ToDateTime(rdr["Date"]);

        int Classroom = Convert.ToInt32(rdr["ClassroomNo"]);

        TimeSpan ST = (TimeSpan)rdr["StartingTime"];
        TimeSpan ET = (TimeSpan)rdr["EndingTime"];
        TimeSpan span = ET.Subtract(ST);
        double Minutesdifference = span.TotalMinutes;

        TimeSpan NewTime = (TimeSpan)rdr["StartingTIme"];

        for (int i = 1; i <= Minutesdifference; i++)
        {
            NewTime = NewTime.Add(TimeSpan.FromMinutes(1));
            // Response.Write(NewTime + "<br>");
            Response.Write(Classroom + "<br>");
            Response.Write(ClassroomNo + "<br>");
            Response.Write(dt + "<br>");
            Response.Write(dt2 + "<br>");
            Response.Write(StartTime + "<br>");
            Response.Write(NewTime + "<br>");
            Response.Write(ST + "<br>");

            if ((Classroom == ClassroomNo && dt == dt2 && StartTime == NewTime) || (Classroom == ClassroomNo && dt == dt2 && StartTime == ST))
            {
                flag = 1;
                break;
            }
            else
            {
                flag = 0;
            }
        }
    }
}

if (flag == 0)
{
    SqlCommand cmd2 = new SqlCommand("spStoreTimeSlotDetails2", con);
    cmd2.CommandType = CommandType.StoredProcedure;

    cmd2.Parameters.AddWithValue("@Username", hfUsername.Value);
    cmd2.Parameters.AddWithValue("@EmpName", lblFacultyName.Text);
    cmd2.Parameters.AddWithValue("@Date", dt);
    cmd2.Parameters.AddWithValue("@Day", day);
    cmd2.Parameters.AddWithValue("@ST", StartTime);
    cmd2.Parameters.AddWithValue("@ET", EndTime);
    cmd2.Parameters.AddWithValue("@TimeSlot", hfTmeSlot.Value);
    cmd2.Parameters.AddWithValue("@Topic", txtTopic.Text);
    cmd2.Parameters.AddWithValue("@ClassroomNo", ClassroomNo);

    cmd2.ExecuteNonQuery();

    lblMessage.ForeColor = System.Drawing.Color.Green;
    lblMessage.Text = "Data Saved Successfully";
}
else if (flag == 1)
{
    lblMessage.ForeColor = System.Drawing.Color.Red;
    lblMessage.Text = "Time Slot already allocated by some other Employee. Please choose another";
}

I write If Condition into for loop. If that condition is true then break the for loop but while(rdr.Read()) method still executing. I just want to close Reader method and directly go out from using(sqlDataReader rdr=cmd.ExecuteReader) method and execute if(flag==0).

Answer 1

My assumption is after breaking from for loop you still want to execute the code in the if loop of flag , so just add this code to break the out of rdr.Read() while loop

else if (flag == 1)
{
  lblMessage.ForeColor = System.Drawing.Color.Red;
  lblMessage.Text = "Time Slot already allocated by some other Employee. Please choose another";
   break;
 }

This code will ensure that Reader object is disposed and closed:

using (SqlDataReader rdr = cmd.ExecuteReader())

So nothing much required beyond the change suggested

Answer 2

while (reader.Read() && !flag)
{
     ....
     for (int i = 1; i <= Minutesdifference; i++)
     {
           if ((Classroom == ClassroomNo && dt == dt2 && StartTime == NewTime) || (Classroom == ClassroomNo && dt == dt2 && StartTime == ST))
                            {
                                flag = 1;

                                break;
                            }
                           else
                           {flag=0;}
                        ...
     }
}

Answer 3

As suggested by Sergei Yevlakov, set flag variable to 0 before the while loop as follows.

using (SqlDataReader rdr = cmd.ExecuteReader())
{
    flag=0;
    while (reader.Read() && !flag)
    {
          .....
           for (int i = 1; i <= Minutesdifference; i++)
           {
                    if ((Classroom == ClassroomNo && dt == dt2 && 
                    StartTime== NewTime) || (Classroom == ClassroomNo && 
                    dt == dt2 && StartTime == ST))
                    {
                            flag = 1;
                            break;
                    }
                    //no need of else part here now.
                    ...
            }
    }
}