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Code execution is not going down

I have a code below and it has strange behavior,Line of code after closing of While Loop is not executing. If i write those lines before While loop they got executed. I have searched a lot on this issue but failed.
if ((Convert.ToInt32(newDt.Rows[i]["qty"])) > (Convert.ToInt32(newDt1.Rows[i]["qty"])))
{
k_batch = Convert.ToInt32(newDt.Rows[i]["batch_num"]);
label20.Content = k_batch.ToString();
var dqty = (from row in Addition_result.AsEnumerable() //retriving value from DataTable
where row.Field<int>("batch_num") == k_batch
select row.Field<int>("qty")).FirstOrDefault();
dqty_y = Convert.ToInt32(dqty);
label16.Content = dqty_y.ToString();
con.Open();
SqlCommand cmd1 = new SqlCommand("SELECT quantity,sold_qty,left_qty FROM batch WHERE id='" + k_batch + "'", con);
SqlDataReader batch_qty_details = null;
batch_qty_details = cmd1.ExecuteReader();
while (batch_qty_details.Read())
{
label16.Content = dqty_y.ToString();
batch_qty = Convert.ToInt32(batch_qty_details["quantity"]);
batch_left = Convert.ToInt32(batch_qty_details["left_qty"]);
batch_sold = Convert.ToInt32(batch_qty_details["sold_qty"]);
} //code after this is not executing
label18.Content = batch_left.ToString();
label19.Content = batch_sold.ToString();
label21.Content = dqty_y.ToString();
label22.Content = batch_qty.ToString();
label16.Content = batch_sold + dqty_y;
label17.Content = batch_left - dqty_y;
if (((batch_sold + dqty_y) <= batch_qty) && ((batch_left - dqty_y) >= 0))
{
SqlCommand command = new SqlCommand("update batch set sold_qty=sold_qty+#soldqty2, left_qty=left_qty-#soldqty2 where id=#id2", con);
command.Parameters.AddWithValue("#soldqty2", Convert.ToInt32(dqty_y));
command.Parameters.AddWithValue("#id2", Convert.ToInt32(k_batch));
rexe = command.ExecuteNonQuery();
}
else
{
MessageBox.Show("Please Check you Ordered Quantity !");
}
con.Close();
}
}

Actually there was issue that connection state was already Open and i was trying to open it again. So then i used try-catch block it told me that connection is already open. Now i have changed my code and here it is.
if ((Convert.ToInt32(newDt.Rows[i]["qty"])) > (Convert.ToInt32(newDt1.Rows[i]["qty"])))
{
k_batch = Convert.ToInt32(newDt.Rows[i]["batch_num"]);
label20.Content = k_batch.ToString();
var dqty = (from row in Addition_result.AsEnumerable() //retriving value from DataTable
where row.Field<int>("batch_num") == k_batch
select row.Field<int>("qty")).FirstOrDefault();
dqty_y = Convert.ToInt32(dqty);
label16.Content = dqty_y.ToString();
try
{
//con.Open();
SqlCommand cmd1 = new SqlCommand("SELECT quantity,sold_qty,left_qty FROM batch WHERE id='" + k_batch + "'", con);
SqlDataReader batch_qty_details = null;
batch_qty_details = cmd1.ExecuteReader();
while (batch_qty_details.Read())
{
label16.Content = dqty_y.ToString();
batch_qty = Convert.ToInt32(batch_qty_details["quantity"]);
batch_left = Convert.ToInt32(batch_qty_details["left_qty"]);
batch_sold = Convert.ToInt32(batch_qty_details["sold_qty"]);
}
con.Close();
}
catch(Exception EX)
{
MessageBox.Show(EX.ToString());
}
label18.Content = batch_left.ToString();
label19.Content = batch_sold.ToString();
label21.Content = dqty_y.ToString();
label22.Content = batch_qty.ToString();
label16.Content = batch_sold + dqty_y;
label17.Content = batch_left - dqty_y;
if (((batch_sold + dqty_y) <= batch_qty) && ((batch_left - dqty_y) >= 0))
{
con.Open();
SqlCommand command = new SqlCommand("update batch set sold_qty=sold_qty+#soldqty2, left_qty=left_qty-#soldqty2 where id=#id2", con);
command.Parameters.AddWithValue("#soldqty2", Convert.ToInt32(dqty_y));
command.Parameters.AddWithValue("#id2", Convert.ToInt32(k_batch));
rexe = command.ExecuteNonQuery();
}
else
{
check_qty = -1;
}
}

If there is no row in database sum command return an error

An error is thrown when there is no data in data base while converting a string value into int.
try {
SqlCommand cmdc = new SqlCommand("SELECT SUM(Credited_amount) FROM IMS_Credit_Dir WHERE Credit_comp_id=1 AND Crdt_typ_id=1", con);
string companya_credit_amount = null, comapnyb_credit_amount = null;
con.Open();
SqlDataReader drc = cmdc.ExecuteReader();
if (drc.HasRows)
{
while (drc.Read())
{
companya_credit_amount = drc[0].ToString();
}
drc.Close();
con.Close();
}
SqlCommand cmdcp = new SqlCommand("SELECT SUM(Credited_amount) FROM IMS_Credit_Dir WHERE Credit_comp_id=2 AND Crdt_typ_id=1", con);
con.Open();
SqlDataReader drcp = cmdcp.ExecuteReader();
if (drcp.HasRows)
{
while (drcp.Read())
{
companyb_credit_amount = drcp[0].ToString();
}
drcp.Close();
con.Close();
}
if (!Page.IsPostBack)
{
int companyA = 0,companyB=0;
if (companya_credit_amount != "") { companyA = Convert.ToInt32(credit_amount.ToString()); }
if (companyb_credit_amount != ""){ companyB = Convert.ToInt32(companyb_credit_amount); }
int total = (companyA+companyB);
count_total_lbl.Text = "Rs." + " " + total.ToString();
count_comapnya_lbl.Text = "Rs." + " " + companya_credit_amount.ToString();
count_companyb_lbl.Text ="Rs."+" "+ companyb_credit_amount.ToString();
}
}
catch(Exception ex) { Label2.Text = ex.ToString(); }
If there is value its working fine.but when there is no value in data base there is an error msg.
System.FormatException: Input string was not in a correct format.

Use IsDBNull to check for null values
Create and destroy all your type instances that implement IDisposable in using blocks. This ensures that connections are always released and resources are cleaned up.
Do not use connections across a class. Create them when needed and then dispose of them. Sql Server will handle connection pooling.
Get the native types directly, not the string equivalent! See changes to GetInt32 instead of ToString on the data reader.
You should refactor this to use SqlParameter's and make the retrieval statement generic OR get both SUM values in 1 sql call.
There is an if (!Page.IsPostBack) statement, if none of this code does anything if it is a postback then check at the top of the page and do not execute the sql statements if it is a postback. Otherwise the code is making (possibly) expensive sql calls for no reason.
try
{
int companyA = 0,companyB=0;
using(var con = new SqlConnection("connectionStringHere"))
{
con.Open();
using(SqlCommand cmdc = new SqlCommand("SELECT SUM(Credited_amount) FROM IMS_Credit_Dir WHERE Credit_comp_id=1 AND Crdt_typ_id=1", con))
using(SqlDataReader drc = cmdc.ExecuteReader())
{
if (drc.Read() && !drc.IsDBNull(0))
companyA = drc.GetInt32(0);
}
using(SqlCommand cmdcp = new SqlCommand("SELECT SUM(Credited_amount) FROM IMS_Credit_Dir WHERE Credit_comp_id=2 AND Crdt_typ_id=1", con))
using(SqlDataReader drcp = cmdcp.ExecuteReader())
{
if (drcp.Read() && !drcp.IsDBNull(0))
companyB = drcp.GetIn32(0);
}
}
// if you are not going to do anything with these values if its not a post back move the check to the top of the method
// and then do not execute anything if it is a postback
// ie: // if (Page.IsPostBack) return;
if (!Page.IsPostBack)
{
int total = (companyA+companyB);
count_total_lbl.Text = "Rs." + " " + total.ToString();
count_comapnya_lbl.Text = "Rs." + " " + companyA.ToString();
count_companyb_lbl.Text ="Rs."+" "+ companyB.ToString();
}
}
catch(Exception ex) { Label2.Text = ex.ToString(); }

Try to replace this
SELECT SUM(Credited_amount)
WITH
SELECT ISNULL(SUM(Credited_amount),0)
Also find one confusing code while converting Credited amount values
if (companya_credit_amount != "") { companyA = Convert.ToInt32(credit_amount.ToString()); }
---------^^^^^
if (companyb_credit_amount != ""){ companyB = Convert.ToInt32(companyb_credit_amount); }
I don't know about your business requirement but What i think Instead of using credit_amount value companya_credit_amount should be use to show value for companyA variable right?

You should do 2 things:
string companya_credit_amount = "", comapnyb_credit_amount = "";
Before assigning the value to these string variable you should check for db null as following:
while (drc.Read())
{
companya_credit_amount = (drc[0] != DbNull.Value) ? drc[0].ToString() : "" ;
}
Similarely
while (drcp.Read())
{
companyb_credit_amount = (drcp[0] != DbNull.Value) ? drcp[0].ToString() : "";
}
Try it.

You need to initialize credit_amount to empty and check if db value is null as shown below:
try {
companya_credit_amount = string.Empty;
companyb_credit_amount = string.Empty;
SqlCommand cmdc = new SqlCommand("SELECT SUM(Credited_amount) FROM IMS_Credit_Dir WHERE Credit_comp_id=1 AND Crdt_typ_id=1", con);
string companya_credit_amount = null, comapnyb_credit_amount = null;
con.Open();
SqlDataReader drc = cmd
c.ExecuteReader();
if (drc.HasRows)
{
while (drc.Read())
{
companya_credit_amount = drcp.IsDBNull(0)?string.Empty:Convert.ToString(drcp[0]);
}
drc.Close();
con.Close();
}
SqlCommand cmdcp = new SqlCommand("SELECT SUM(Credited_amount) FROM IMS_Credit_Dir WHERE Credit_comp_id=2 AND Crdt_typ_id=1", con);
con.Open();
SqlDataReader drcp = cmdcp.ExecuteReader();
if (drcp.HasRows)
{
while (drcp.Read())
{
companyb_credit_amount = drcp.IsDBNull(0)?string.Empty:Convert.ToString(drcp[0]);
}
drcp.Close();
con.Close();
}
if (!Page.IsPostBack)
{
int companyA = 0,companyB=0;
if (companya_credit_amount != "") { companyA = Convert.ToInt32(credit_amount.ToString()); }
if (companyb_credit_amount != ""){ companyB = Convert.ToInt32(companyb_credit_amount); }
int total = (companyA+companyB);
count_total_lbl.Text = "Rs." + " " + total.ToString();
count_comapnya_lbl.Text = "Rs." + " " + companya_credit_amount.ToString();
count_companyb_lbl.Text ="Rs."+" "+ companyb_credit_amount.ToString();
}
}
catch(Exception ex) { Label2.Text = ex.ToString(); }

c#.net Error: There is already an open DataReader associated with this Command which must be closed first

Help, I am new to asp.net c#. I tried the codes once before but it didn't seems to have this error. So I can't seems to figure where do I make changes to.
Sever error :
There is already an open DataReader associated with this Command which must be closed first.
Codes:
string strConnectionString = ConfigurationManager.ConnectionStrings["FYPDB"].ConnectionString;
SqlConnection myConnect = new SqlConnection(strConnectionString);
string strCommandText = "select promoId FROM FYPDB.dbo.Promotions where membershipType LIKE '%' + #membership + '%' AND defaults LIKE '%' + #defaults + '%'";
try
{
string ddlmembership = ((DropDownList)dvInsertPromotion.FindControl("ddlAddMembershiplist")).SelectedItem.ToString();
string ddlDefault = ((RadioButtonList)dvInsertPromotion.FindControl("RadioButtonList2")).Text.ToString();
DataSet da = dal.retrieveMembership(ddlmembership, ddlDefault);
SiteGridView.DataSource = da;
SiteGridView.DataBind();
SqlCommand cmd = new SqlCommand(strCommandText, myConnect);
cmd.Parameters.Add("#membership", SqlDbType.NVarChar);
cmd.Parameters.Add("#defaults", SqlDbType.NVarChar);
cmd.Parameters["#membership"].Value = ddlmembership;
cmd.Parameters["#defaults"].Value = ddlDefault;
myConnect.Open();
SqlDataReader reader = cmd.ExecuteReader();
if (reader.Read())
{
//get number of count
//int count = da.Tables[0].Rows.Count;
int count = (int)cmd.ExecuteScalar();
if (count == 1)
{
defaultComfirm.Show();
promotion = false;
}
}
else
{
Label6.Text = "error didnt go through";
Label6.ForeColor = System.Drawing.Color.Gray;
Label6.Visible = true;
}
reader.Close();
}
finally
{
myConnect.Close();
}

you are using the same command object two times:
SqlDataReader reader = cmd.ExecuteReader();
int count = (int)cmd.ExecuteScalar();
This is not possible.
It is not necessary to use a reader if you just want to have the count of rows. In this case you can use the ExecuteScalar.
Like this:
string strCommandText = "select COUNT(promoId) FROM FYPDB.dbo.Promotions where membershipType LIKE '%' + #membership + '%' AND defaults LIKE '%' + #defaults + '%'";
try
{
...
int count = (int)cmd.ExecuteScalar();
...
Regards
Oliver

Looking at your code, you just need count of rows matching the criteria.
So if you just need rows count you could use any of these options.
Option 1:
Find out count by reading all rows
int count =0;
while(reader.Read()) count++;
if (count == 1)
{
defaultComfirm.Show();
promotion = false;
}
else
{
...
}
reader.Close();
Option 2:
My preferred choice for this case, Modify your query to return the count (SELECT COUNT(*)).
string strCommandText = "select count(promoId) FROM FYPDB.dbo.Promotions where membershipType LIKE '%' + #membership + '%' AND defaults LIKE '%' + #defaults + '%'";
now,
int count = (int)cmd.ExecuteScalar();
if (count == 1)
{
defaultComfirm.Show();
promotion = false;
}
else
{
...
}
reader.Close();
Option 3:
Other option to convert it to DataTable and get the row count.
using (DataTable dt = new DataTable())
{
dt.Load(reader);
if (dt.Rows.Count == 1)
{
defaultComfirm.Show();
promotion = false;
}
else
{
...
}
reader.Close();
}

try to execute cmd.ExecuteScalar() before cmd.ExecuteReader().
int count = (int)cmd.ExecuteScalar();
SqlDataReader reader = cmd.ExecuteReader();
if (reader.Read())
{
//get number of count
//int count = da.Tables[0].Rows.Count;
if (count == 1)
{
defaultComfirm.Show();
promotion = false;
}
}

Removing duplicates in a MS Access database

I was trying to remove duplicates from the table Main.
It looks like this(here in csv form):
"Record ID";Status;Placement;Private;Category;Note;Blob
for instance
14341692;132;2147483647;False;4;"29.12.10 14:17";System.Byte[]
Duplicates means, Note is the same. My approach is this:
string strSQL = "SELECT * FROM Main";
OleDbCommand cmd = new OleDbCommand(strSQL, MemoVerbindung);
OleDbDataReader dr = cmd.ExecuteReader();
_items = new List<string>(); // <-- Add this
while (dr.Read())
{
if (dr.FieldCount >= 5)
_items.Add(dr[5].ToString());
}
dr.Close();
progressBar1.Maximum = _items.Count;
for (int a = 0; a < _items.Count; a++)
{
progressBar1.Value = a;
strSQL = "SELECT * FROM Main WHERE Note = '" + _items[a].ToString().Replace("'", "\'") + "'";
cmd = new OleDbCommand(strSQL, MemoVerbindung);
dr = null;
OleDbDataReader dr2 = null;
try
{
dr = cmd.ExecuteReader();
int u = 0;
if (dr.FieldCount > 1)
{
while (dr.Read())
{
if (u >= 1)
{
string was = "DELETE FROM Main WHERE [Record ID] = " + dr[0];
OleDbCommand command = new OleDbCommand(was, MemoVerbindung);
OleDbDataReader reader = command.ExecuteReader();
while (reader.Read())
{
//MessageBox.Show(reader[0].ToString());
}
reader.Close();
}
u++;
}
}
else
{
while (dr.Read())
{
MessageBox.Show("Übrig");
}
}
dr.Close();
}
catch (Exception mm)
{
//MessageBox.Show(mm.Message);
}
}
MessageBox.Show("Fertig");
progressBar1.Value = 0;
So in the if (u >= 1) section I am trying to leave one version while removing all others. Unfortunately that does not work meaning all entries are removed but the ones raising an error for a reason. What would you change or is there a generally more elegant way?

Use this SQL statement to find the duplicates:
SELECT First(Main.[Note]) AS [NoteField], Count(Main.[Note]) AS NumberOfDups
FROM Main
GROUP BY Main.[Note]
HAVING (((Count(Main.[Note]))>1));
then you can loop through this recordset (grab it as a SnapShot so changes to the underlying data does not change the results)
use !NoteField to know which note to find, and !NumberOfDups to know how many you have to delete (remove this number - 1)

Is it possible to use ExecuteReader() twice?

I'm programming a database manager for a gameserver called OTServer, and I'm having problems using executereader() the second time. Here's code:
private void button1_Click(object sender, EventArgs e)
{
Form1 f = new Form1();
MySqlConnection conn = new MySqlConnection();
conn.ConnectionString = "Server=" + f.GetText1().Text + ";Username=" + f.GetText2().Text + ";Pwd=" + f.GetText3().Text + ";Database=" + f.GetText4().Text + ";";
conn.Open();
MySqlCommand cmd = new MySqlCommand("SELECT * FROM `players` WHERE name = #Name", conn);
cmd.Parameters.AddWithValue("#Name", textBox1.Text);
MySqlDataReader Reader = cmd.ExecuteReader(CommandBehavior.SingleRow);
while (Reader.Read())
{
label7.Text = (string)Reader[1];
label7.Show();
label8.Text = Reader[5].ToString();
label8.Show();
if ((int)Reader[6] == 1)
{
label9.Text = "Sorcerer (1)";
}
if ((int)Reader[6] == 2)
{
label9.Text = "Druid (2)";
}
if ((int)Reader[6] == 3)
{
label9.Text = "Paladin (3)";
}
if ((int)Reader[6] == 4)
{
label9.Text = "Knight (4)";
}
if ((int)Reader[6] == 0)
{
label9.Text = "None (0)";
}
label9.Show();
if ((int)Reader[3] == 1)
{
label10.Text = "Player";
}
if ((int)Reader[3] == 2)
{
label10.Text = "Tutor";
}
if ((int)Reader[3] == 3)
{
label10.Text = "Senior Tutor";
}
if ((int)Reader[3] == 4)
{
label10.Text = "Gamemaster";
}
if ((int)Reader[3] == 5)
{
label10.Text = "Community Manager";
}
if ((int)Reader[3] == 6)
{
label10.Text = "God";
}
if ((int)Reader[3] < 1 || (int)Reader[3] > 6)
{
label10.Text = "Unknown";
}
label10.Show();
label13.Text = "Account: " + Reader[4].ToString();
label13.Show();
}
Reader.Close();
cmd = new MySqlCommand("SELECT * FROM accounts WHERE id = #Account_ID", conn);
cmd.Parameters.AddWithValue("#Account_ID", label13.Text);
Reader = cmd.ExecuteReader(CommandBehavior.SingleRow);
while (Reader.Read())
{
label11.Text = (string)Reader[0];
label11.Show();
}
Reader.Close();
}

Suggested solution: Try putting a using block around your DataReader, or call Dispose on it:
using (DataReader Reader = cmd.ExecuteReader(CommandBehavior.SingleRow))
{
// ...do something with your data reader... then finish by:
Reader.Close();
} // <-- Reader.Dispose() called automatically at the end of using block.
// ...prepare second command...
// the same again for the second command:
using (DataReader Reader = cmd.ExecuteReader(CommandBehavior.SingleRow))
{
// ...
Reader.Close();
}
Assumed cause of your problem: The DB connection object may do some internal book-keeping to keep track of data readers. I've found out in a similar scenario that you're only allowed one DataReader at a time. So I believe the problem with your code is that, while you Close the Reader, you haven't explicitly Disposed it, so the connection object thinks the first data reader is still in use when you execute the second one.
Besides... why not simplify this code:
if ((int)Reader[6] == 1)
{
label9.Text = "Sorcerer (1)";
}
if ((int)Reader[6] == 2)
{
label9.Text = "Druid (2)";
}
...
to a switch statement?:
int x = (int)(Reader[6]);
string label9Text = string.Empty;
switch (x)
{
case 1: label9Text = "Sorcerer (1)"; break;
case 2: label9Text = "Druid (2)"; break;
...
}
label9.Text = label9Text;
(That would save you quite a bit of repetitive typing.)

Well, assuming that your code is correct you shouldn't have problem in executing two readers as you show in your code. Maybe you have problems because of not disposing commands or something else. I recommend an approach like this (Example made with Northwind db):
using (SqlConnection connection = new SqlConnection("Data Source=.\\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=SSPI;"))
{
connection.Open();
using (SqlCommand command = new SqlCommand("SELECT * FROM Orders", connection))
{
using (SqlDataReader reader = command.ExecuteReader(System.Data.CommandBehavior.SingleRow))
{
while (reader.Read())
{
Console.WriteLine(reader.GetString(2));
}
}
}
using (SqlCommand command = new SqlCommand("SELECT * FROM Products", connection))
{
using (SqlDataReader reader = command.ExecuteReader(System.Data.CommandBehavior.SingleRow))
{
while (reader.Read())
{
Console.WriteLine(reader.GetString(1));
}
}
}
}
You should clean your code when recognizing the type of player. Create an enum instead:
public enum PlayerType
{
None = 0,
Sorcerer = 1,
Druid = 2,
Paladin = 3
}
And then do the following while reading:
PlayerType playerType = (PlayerType)reader.GetInt32(6);
label9.Text = playerType.ToString();