I want to retrieve Absent student names from sql database. I have a Listbox in which i have Present student Rfid data (Something like 42 39 A0 11), I have stored the student details along with Rfid in database as nvarchar(1500) datatype.
Using the present stud id in list box i want to retrieve absent students name in an array.
I used NOT IN condition in where but i was not able to retrieve
Then i thought of using for loops to match the get the students who's id was not in the Listbox
But still I am losing the values and not getting proper absent students Id.
- private void checkabst_Click(object sender, EventArgs e)
- {
- string[] present = new string[3];
- string[] absent = new string[3];
- string[] allstd = new string[3];
- List<string> total = new List<string>();
- using (SqlConnection con = new SqlConnection(cs))
- {
- SqlCommand cmd = new SqlCommand("Select Rfid_Uid From Studetails", con);
- con.Open();
- SqlDataReader sdr = cmd.ExecuteReader();
- while (sdr.Read())
- {
- total.add(sdr[0].ToString());
- }
- allstd=total.toArray();
- for(int i=0;i
- {
- present[i] = listbox_present.Items[i].ToString();
- }
- bool isfound = false;
- for (int i = 0; i < 3; i++)
- {
- isfound = false;
- for (int j = 0; j < present.Length; j++)
- {
- if (allstd[i] == present[j])
- {
- isfound = true;
- }
- }
- if (!isfound)
- {
- MessageBox.Show(allstd[i]);
- }
- }
Stuck here from past few days.
I am getting Present as well as the absent student Ids in messagebox.