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SQL DataReader: Invalid attempt to read when no data is present to label

I am trying to use a SqlDataReader to run queries on two tables where the 1st column in the Selection table is a foreign key referencing to the Items table, and then display the results in labels, but I keep getting the error:
Invalid attempt to read when no data is present.
Here is my code:
public partial class Read : System.Web.UI.Page
{
SqlConnection conn = new SqlConnection(#"data source = localhost; integrated security = true; database = dev_handin1");
SqlCommand cmd = null;
SqlDataReader rdr = null;
string sqlsel = "SELECT MainItemId FROM Selection";
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
GetInfo();
}
}
private void GetInfo() {
try
{
cmd = new SqlCommand(sqlsel, conn);
conn.Open();
sqlsel = "SELECT * FROM Items WHERE ItemId = MyMainItem";
rdr = cmd.ExecuteReader();
var MyMainItem = rdr[0];
while (rdr.Read())
{
LabelCategory1.Text = rdr[1].ToString();
LabelHeadline1.Text = rdr[2].ToString();
LabelText1.Text = rdr[3].ToString();
LabelJoke1.Text = rdr[4].ToString();
}
}
catch (Exception ex)
{
LabelMessage1.Text = ex.Message;
}
finally
{
rdr.Close();
conn.Close();
}
}
}
}
I'm pretty new at this so please bear with me.

C# How to Update/Change the specific letter/number of a string in database

I ask these question coz i really don't know how i'm gonna do that and is it possible to do that?
What i want is to update/change here for example STA-100418-100 in database values, update/change the 100 based on the user input, like 50 it will be STA-100418-50.
Here's the provided image to be more precise
As you can see on the image, there's a red line, if user update the quantity as 60, In Codeitem STA-100418-100 should be STA-100418-60
I really have no idea on how to do that. I hope someone would be able to help me
here's my code for updating the quantity
private void btn_ok_Click(object sender, EventArgs e)
{
using (var con = SQLConnection.GetConnection())
{
using (var selects = new SqlCommand("Update Product_Details set quantity = quantity - #Quantity where ProductID= #ProductID", con))
{
selects.Parameters.Add("#ProductID", SqlDbType.VarChar).Value = _view.txt_productid.Text;
selects.Parameters.Add("#Quantity", SqlDbType.Int).Value = Quantity;
selects.ExecuteNonQuery();
}
}
}
Here's the code to get that format in codeitems
string date = DateTime.Now.ToString("MMMM-dd-yyyy");
string shortdate = DateTime.Now.ToString("-MMddy-");
private void Quantity_TextChanged(object sender, EventArgs e)
{
Code.Text = Supplier.Text.Substring(0, 3) + shortdate + Quantity.Text;
}

Here's what I use to update SQL-Server
public static DataTable GetSqlTable(string sqlSelect)
{
string conStr = ConfigurationManager.ConnectionStrings["connString"].ConnectionString;
DataTable table = new DataTable();
SqlConnection connection = new SqlConnection(conStr);
try
{
connection.Open();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
if (connection.State != ConnectionState.Open)
{
return table;
}
SqlCommand cmd = new SqlCommand(sqlSelect, connection);
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
try
{
adapter.Fill(table);
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
throw;
}
connection.Close();
connection.Dispose();
return table;
}
public static void GetSqlNonQuery(string sqlSelect)
{
string newObject = string.Empty;
string strConn = ConfigurationManager.ConnectionStrings["connString"].ConnectionString;
SqlConnection connection = new SqlConnection(strConn);
connection.Open();
if (connection.State != ConnectionState.Open)
{
return;
}
try
{
SqlCommand cmd = new SqlCommand(sqlSelect, connection);
cmd.ExecuteNonQuery();
connection.Close();
connection.Dispose();
}
catch (Exception ex)
{
string x = ex.Message + ex.StackTrace;
throw;
}
}
Here's how to use it
DataTable dt = GetSqlTable("select Quantity from product where CodeItem = 'STA-100418-100'");
string strQuantity = dt.Rows[0]["Quantity"].ToString();
GetSqlNonQuery(string.Format("UPDATE product SET CodeItem = '{0}' WHERE = 'STA-100418-100'", strQuantity));

User will input everytime in the Quantity textbox, the textchanged event of Quantity will be hit and you will get new value everytime with the same date but with different quantity. So you can use the Code.Text to update the CodeDateTime value or you can use a global variable instead of Code.Text and use it to update the column.
string date = DateTime.Now.ToString("MMMM-dd-yyyy");
string shortdate = DateTime.Now.ToString("-MMddy-");
private void Quantity_TextChanged(object sender, EventArgs e)
{
Code.Text = Supplier.Text.Substring(0, 3) + shortdate + Quantity.Text;
}
using (var con = SQLConnection.GetConnection())
{
using (var selects = new SqlCommand("Update Product_Details set quantity = quantity - #Quantity, CodeItem = #Code where ProductID= #ProductID", con))
{
selects.Parameters.Add("#ProductID", SqlDbType.VarChar).Value = _view.txt_productid.Text;
selects.Parameters.Add("#Quantity", SqlDbType.Int).Value = Quantity;
selects.Parameters.Add("#Code", Code.Text);
}
}

as I understand it you need MSSQL String Functions
SELECT rtrim(left(Codeitem,charindex('-', Codeitem))) + ltrim(str(Quantity)) FROM ...
For detailed information

Using MySql, Substring the code item and then concatenate the quantity.
UPDATE Product_Details SET quantity = #quantity,CodeIem = CONCAT(SUBSTR(#code,1,11),#quantity) WHERE ProductID= #ProductID

C# update statement not updating when update button clicked

i am creating c# project so far insert and delete buttons are working but when i hit update button it gives data has not been updated and i cant see what is wrong with my code please help
public bool Update(Classre c)
{
bool isSuccess = false;
SqlConnection conn = new SqlConnection(myconnstring);
try
{
string sql = "UPDATE Class SET ClassName=#ClassName,ClassLevel=#ClassLevel WHERE ClassID=#ClassID";
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.AddWithValue("#ClassName", c.ClassName);
cmd.Parameters.AddWithValue("#ClassLevel", c.ClassLevel);
conn.Open();
int rows = cmd.ExecuteNonQuery();
if (rows > 0)
{
isSuccess = true;
}
else
{
isSuccess = false;
}
}
catch (Exception ex)
{
}
finally
{
conn.Close();
}
return isSuccess;
}
and this is my update button code where i call the class that holds my update code
private void button3_Click(object sender, EventArgs e)
{
c.ClassID = int.Parse(textBox1.Text);
c.ClassName = textBox2.Text;
c.ClassLevel = comboBox1.Text;
bool success = c.Update(c);
if (success == true)
{
// label4.Text = "Data Has been updated";
MessageBox.Show("Data Has been updated");
DataTable dt = c.Select();
dataGridView1.DataSource = dt;
}
else
{
//label4.Text = "Data Has not been updated";
MessageBox.Show("Data Has not been updated");
}
}

I would prefer to use a stored procedure instead of pass through sql but you could greatly simplify this. As stated above your try/catch is worse than not having one because it squelches the error.
public bool Update(Classre c)
{
USING(SqlConnection conn = new SqlConnection(myconnstring))
{
string sql = "UPDATE Class SET ClassName = #ClassName, ClassLevel = #ClassLevel WHERE ClassID = #ClassID";
USING(SqlCommand cmd = new SqlCommand(sql, conn))
{
cmd.Parameters.Add("#ClassName", SqlDbType.VarChar, 4000).Value = c.ClassName;
cmd.Parameters.Add("#ClassLevel", SqlDbType.Int).Value = c.ClassLevel;
cmd.Parameters.Add("#ClassID", SqlDbType.Int).Value = c.ClassID;
conn.Open();
int rows = cmd.ExecuteNonQuery();
return rows > 0;
}
}
}

Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool.

I am getting this error
Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.
I read this question and it states that the exception is caused because of not closing the connection. However, i close all the connection in my code
This is my code, it is simple
public partial class index : System.Web.UI.Page
{
private static string defaultReason = "reason not selected";
protected override object SaveViewState()
{
//save view state right after the dynamic controlss added
var viewState = new object[1];
viewState[0] = base.SaveViewState();
return viewState;
}
protected override void LoadViewState(object savedState)
{
//load data frm saved viewstate
if (savedState is object[] && ((object[])savedState).Length == 1)
{
var viewState = (object[])savedState;
fillReasons();
base.LoadViewState(viewState[0]);
}
else
{
base.LoadViewState(savedState);
}
}
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
string callIDValue = Request.QueryString["CallID"];
string callerIDValue = Request.QueryString["CallerID"];
if (!String.IsNullOrEmpty(callerIDValue))
{
callerID.Value = callerIDValue;
if (!String.IsNullOrEmpty(callIDValue))
{
string query = "INSERT INTO Reason (callerID, callID, reason, timestamp) VALUES (#callerID, #callID, #reason, #timestamp)";
SqlConnection con = getConnection();
SqlCommand command = new SqlCommand(query, con);
command.Parameters.AddWithValue("#callerID", callerIDValue);
command.Parameters.AddWithValue("#callID", callIDValue);
command.Parameters.AddWithValue("#reason", defaultReason);
command.Parameters.AddWithValue("#timestamp", DateTime.Now.ToString());
try
{
con.Open();
command.ExecuteNonQuery();
command.Dispose();
con.Close();
}
catch (Exception ee)
{
command.Dispose();
con.Close();
message.InnerHtml = ee.Message;
}
}
else
{
message.InnerHtml = "Call ID is empty";
}
}
else
{
callerID.Value = "Undefined";
message.InnerHtml = "Caller ID is empty";
}
fillReasons();
}
else
{
}
}
private void fillReasons()
{
string query = "SELECT * FROM wrapuplist WHERE isEnabled = #isEnabled";
SqlConnection con = new SqlConnection(getConnectionString());
SqlCommand cmd = new SqlCommand(query, con);
cmd.Parameters.AddWithValue("isEnabled", true);
con.Open();
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable results = new DataTable();
da.Fill(results);
int numberOfReasons = 0; // a integer variable to know if the number of the reasons becomes able to be divided by four
HtmlGenericControl div = null;
foreach (DataRow row in results.Rows)
{
numberOfReasons++;
if ((numberOfReasons % 4) == 1)
{
div = new HtmlGenericControl("div");
div.Attributes.Add("class", "oneLine");
}
RadioButton radioButton = new RadioButton();
radioButton.ID = "reason_" + row["reasonName"].ToString();
radioButton.GroupName = "reason";
radioButton.Text = row["reasonName"].ToString();
div.Controls.Add(radioButton);
if (numberOfReasons % 4 == 0)
{
myValueDiv.Controls.Add(div);
//numberOfReasons = 0;
}
else if (numberOfReasons == results.Rows.Count)
{
myValueDiv.Controls.Add(div);
//numberOfReasons = 0;
}
}
cmd.Dispose();
da.Dispose();
con.Close();
}
private SqlConnection getConnection()
{
return new SqlConnection(ConfigurationManager.ConnectionStrings["vmpcon"].ConnectionString);
}
private string getConnectionString()
{
return ConfigurationManager.ConnectionStrings["wrapupconnection"].ConnectionString.ToString();
}
protected void buttonSaveClose_Click(object sender, EventArgs e)
{
var divcontrols = myValueDiv.Controls.OfType<HtmlGenericControl>();
bool isFound = false;
RadioButton checkedRadioButton = null;
foreach (HtmlGenericControl loHTML in divcontrols)
{
var checkedRadioButtons = loHTML.Controls.OfType<RadioButton>().Where(radButton => radButton.Checked).ToList();
foreach (RadioButton lobtn in checkedRadioButtons)
{
if (lobtn.Checked)
{
isFound = true;
checkedRadioButton = lobtn;
}
}
}
if (isFound)
{
sReasonError.InnerText = "";
string reason = "";
reason = checkedRadioButton.Text;
string callIDValue = Request.QueryString["CallID"];
string callerIDValue = Request.QueryString["CallerID"];
if (String.IsNullOrEmpty(callIDValue))
{
message.InnerText = "Call ID is empty";
}
else if (String.IsNullOrEmpty(callerIDValue))
{
message.InnerText = "Caller ID is empty";
}
else
{
message.InnerText = "";
string query2 = "SELECT * FROM Reason WHERE callID = #callID AND reason != #reason";
SqlConnection con = getConnection();
SqlCommand command2 = new SqlCommand(query2, con);
command2.Parameters.AddWithValue("#callID", callIDValue);
command2.Parameters.AddWithValue("#reason", defaultReason);
con.Open();
if (command2.ExecuteScalar() != null)
{
message.InnerText = "Already saved";
command2.Dispose();
con.Close();
}
else
{
command2.Dispose();
con.Close();
string notes = taNotes.InnerText;
string query = "UPDATE Reason SET reason = #reason, notes = #notes, timestamp = #timestamp WHERE callID = #callID";
SqlCommand command = new SqlCommand(query, con);
command.Parameters.AddWithValue("#callID", callIDValue);
command.Parameters.AddWithValue("#reason", reason);
command.Parameters.AddWithValue("#notes", notes);
command.Parameters.AddWithValue("#timestamp", DateTime.Now.ToString());
try
{
con.Open();
command.ExecuteNonQuery();
command.Dispose();
con.Close();
message.InnerText = "Done Successfully";
//ClientScript.RegisterStartupScript(typeof(Page), "closePage", "<script type='text/JavaScript'>window.close();</script>");
ClientScript.RegisterStartupScript(typeof(Page), "closePage", "window.open('close.html', '_self', null);", true);
}
catch (Exception ee)
{
command.Dispose();
con.Close();
message.InnerText = "Error, " + ee.Message;
}
}
}
}
else
{
sReasonError.InnerText = "Required";
message.InnerText = "Select a reason";
//fillReasons();
}
}
}
as you see, all the connection are being closed, what wrong did I do please?

Closing connections and disposing should be in a finally block while using a try catch.
or use a using block like the one below
using(SqlConnection con = getConnection())
{
con.Open();
//Do your operation here. The connection will be closed and disposed automatically when the using scope is exited
}

C# - Populating a List with data from a database

I have a List (listOfQuestionIDs) stored in ViewState of 10 different numbers and an int counter (questionCounter) stored in ViewState which I intend to use to access the different numbers in the first list.
However, as I increment the value of ViewState["questionCounter"] by 1 the contents of listOfAnswerIDs and listOfAnswers remain exactly the same in the code below. Why is this?
protected void getAnswers()
{
string connStr = ConfigurationManager.ConnectionStrings["myConnectionString"].ConnectionString;
MySqlConnection conn = new MySqlConnection(connStr);
MySqlDataReader reader;
List<int> listOfQuestionIDs = (List<int>)(ViewState["listOfQuestionIDs"]);
int questionCounter = Convert.ToInt32(ViewState["questionCounter"]);
List<string> listOfAnswerIDs = new List<string>();
List<string> listOfAnswers = new List<string>();
List<string> listOfCorrectAnswerIDs = new List<string>();
try
{
conn.Open();
string cmdText = "SELECT * FROM answers WHERE question_id=#QuestionID";
MySqlCommand cmd = new MySqlCommand(cmdText, conn);
cmd.Parameters.Add("#QuestionID", MySqlDbType.Int32);
cmd.Parameters["#QuestionID"].Value = Convert.ToInt32(listOfQuestionIDs[questionCounter]);
reader = cmd.ExecuteReader();
while (reader.Read())
{
listOfAnswerIDs.Add(reader["answer_id"].ToString());
listOfAnswers.Add(reader["answer"].ToString());
if (reader["correct"].ToString().Equals("Y"))
{
listOfCorrectAnswerIDs.Add(reader["answer_id"].ToString());
}
}
for (int i = 0; i < listOfAnswerIDs.Count; i++)
{
lblTitle.Text += listOfAnswerIDs[i].ToString();
}
reader.Close();
populateAnswers(listOfAnswerIDs.Count, listOfAnswers, listOfAnswerIDs);
}
catch
{
lblError.Text = "Database connection error - failed to read records.";
}
finally
{
conn.Close();
}
ViewState["listOfQuestionIDs"] = listOfQuestionIDs;
ViewState["listOfCorrectAnswerIDs"] = listOfCorrectAnswerIDs;
}
Here's where I increment the questionCounter:
protected void btnNext_Click(object sender, EventArgs e)
{
.........
getNextQuestion();
}
protected void getNextQuestion()
{
int questionCounter = Convert.ToInt32(ViewState["QuestionCounter"]);
..........
getAnswers();
................
questionCounter += 1;
ViewState["QuestionCounter"] = questionCounter;
}

ViewState keys are case sensitive. In getAnswers() you use "questionCounter" and in getNextQuestion() you use "QuestionCounter". Pick one and keep it consistent.