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How to fix code to return full list instead of one row from SqlDataReader in C# Web API

I am building a web API that connects to SQL and am trying to return all rows from the db in which the "StartDateTime" value is equal to today's date. For some reason, I am only getting one row instead of all rows that fit the definition. What do I need to change?
public class EventsController : ApiController
{
public List<tblEventDate> Get()
{
using (CalendarEntities entities = new CalendarEntities())
{
tblEventDate singleEvent = new tblEventDate();
List<tblEventDate> eventList = new List<tblEventDate>();
string strcon = ConfigurationManager.ConnectionStrings["DbConnCalendar"].ConnectionString;
SqlConnection con = new SqlConnection(strcon);
con.Open();
string comm = "SELECT [dbo].[tblEventDates].[EventID], [dbo].[tblEventDates].[StartDateTime], WHERE (CONVERT(date, dbo.tblEventDates.StartDateTime) = CONVERT(date, GETDATE()))";
SqlCommand cmd = new SqlCommand(comm, con);
using (SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.HasRows)
{
while (reader.Read())
{
singleEvent.StartDateTime = (DateTime)(reader["StartDateTime"]);
singleEvent.EventID = (long)reader["EventID"];
eventList.Add(singleEvent);
}
reader.NextResult();
}
con.Close();
}
return eventList;
}
}
}

Try this:
conn.Open();
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
while (reader.Read())
{
if (reader.HasRows)
{
singleEvent.StartDateTime = (DateTime)(reader["StartDateTime"]);
singleEvent.EventID = (long)reader["EventID"];
eventList.Add(singleEvent);
}
}

How can I send response from c# class file to MVC Controller

If my condition fails as rdr.HasRows == true, how can I respond my controller its fails
public Employee DeleteEmpById(int key)
{
try
{
SqlCommand cmd = new SqlCommand("Sp_GetEmployeeById", con);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#EmpId", key);
SqlDataReader rdr = cmd.ExecuteReader();
if (rdr.HasRows == true)
{
}
else
// Here what I mention when rdr.HasRows false
}
Controller
public ActionResult DeleteById(int id)
{
var x = ObjRepo.DeleteEmpById(id);
return View(x);
}

Use While Read
Bool HasData =False ;
SqlDataReader rdr = cmd.ExecuteReader();
while (rdr.Read())
{
// If there is A row sqlDataReader Will read
HasData =true ;
break; // you only have to check one time , performance improve
}
return HasData

Can I execute multiple SQL statements?

I am running an sql database for movies and I am working on this function so that whenever a user checks out a movie, the movie would be updated saying it has been checked out, then the checked out movie would be added to a table for checked out movies. I have a code that runs without any errors but my checked out movie does not get added to my checked out table. Code for the gridview that displays the selected movie below:
<asp:ListBox ID="CheckOutList" runat="server" OnSelectedIndexChanged="Get_data" AutoPostBack="true">
</asp:ListBox>
<asp:Panel ID="panel5" runat="server" Visible="false">
<asp:GridView id="one_data" AutoGenerateColumns="false" runat="server" DataKeyNames="MovieID">
<Columns>
<asp:BoundField DataField="MovieID"
HeaderText="Movie ID"/>
<asp:BoundField DataField="MovieTitle"
HeaderText="Movie"/>
<asp:BoundField DataField="DateChecked"
HeaderText="Date Checked"/>
<asp:BoundField DataField="CheckedOut"
HeaderText="Checked Out"/>
</Columns>
</asp:GridView>
<asp:Button runat="server" Text="Choose another Movie" OnClick="GoBack" />
<asp:Button runat="server" Text="Check Out" OnClick="CheckOut" />
</asp:Panel>
CS code for checking out the movie:
public void CheckOut(object sender, EventArgs e)
{
get_connection();
try
{
connection.Open();
command = new SqlCommand("UPDATE Content SET DateChecked=#DateChecked, CheckedOut=#CheckedOut WHERE MovieID=#MovieID", connection);
command.Parameters.AddWithValue("#DateChecked", DateTime.Now);
command.Parameters.AddWithValue("#CheckedOut", 'Y');
//command.Parameters.AddWithValue("#MovieID",);
command.Parameters.AddWithValue("#MovieID", CheckOutList.SelectedValue);
reader = command.ExecuteReader();
one_data.DataSource = reader;
one_data.DataBind();
reader.Close();
command = new SqlCommand("INSERT INTO checkout (MovieID, SubscriberID) VALUES #MovieID, #SubscriberID", connection);
command.Parameters.AddWithValue("#MovieID", CheckOutList.SelectedValue);
command.Parameters.AddWithValue("#SubscriberID", loginName.Text);
command.ExecuteNonQuery();
}
catch (Exception err)
{
// Handle an error by displaying the information.
lblInfo.Text = "Error reading the database. ";
lblInfo.Text += err.Message;
}
finally
{
connection.Close();
lblInfo.Text = "Movie Checked Out";
}
}
The UPDATE SQL statement does work saying the movie has been taken but the movie does not get added to the checked out table.

I see some missing concept.
why update use command.ExecuteReader(); while insert use command.ExecuteNonQuery(); .
I think you should use
ExecuteNonQuery
INSERT INTO checkout (MovieID, SubscriberID) VALUES #MovieID, #SubscriberID .
This sql syntax need bracket for values :
INSERT INTO checkout (MovieID, SubscriberID) VALUES (#MovieID, #SubscriberID)
I hope this solve yours.

I think you better execute coding in the transaction block. also you can update as following examlpe with ";"
connection.ConnectionString = connectionString;
command.CommandText = #"
UPDATE MultiStatementTest SET somevalue = somevalue + 1;
UPDATE MultiStatementTest SET" + (generateError ? "WONTWORK" : "") +
" somevalue = somevalue + 2;";
command.CommandType = System.Data.CommandType.Text;
command.Connection = connection;

Can I execute multiple SQL statements?
Of course you can! You can execute it in a single or multiple SqlCommand. :)
The UPDATE SQL statement does work saying the movie has been taken but
the movie does not get added to the checked out table
Are you using a local database? If yes, check out Data not saving permanently to SQL table.
Anyway, I would like to my code for data access which could help you in your development.
Disclaimer: I know that using SqlCommand as parameter is better but I got lazy so here's the string version.
public interface IDAL
{
void BeginTransaction();
void EndTransaction();
void SaveChanges();
DataTable RetrieveData(string query, [CallerMemberName] string callerMemberName = "");
string RetrieveString(string query, [CallerMemberName] string callerMemberName = "");
bool ExecuteNonQuery(string query, [CallerMemberName] string callerMemberName = "");
bool ExecuteNonQuery(string query, object[] parameters, [CallerMemberName] string callerMemberName = "");
}
public class MSSQLDAL : IDAL, IDisposable
{
private bool disposed = false;
private string _connectionString { get; set; }
private SqlTransaction _transaction { get; set; }
private SqlConnection _connection { get; set; }
private IsolationLevel _isolationLevel { get; set; }
private bool _isCommitted { get; set; }
public string ConnectionString
{
get { return _connectionString; }
}
public MSSQLDAL(string connectionString)
{
this.connectionString = _connectionString;
this._connection = new SqlConnection();
this._connection.ConnectionString = this._connectionString;
this._isolationLevel = IsolationLevel.ReadCommitted;
this._isCommitted = false;
}
public void BeginTransaction()
{
this.Open();
}
public void EndTransaction()
{
this.Close();
}
public void SaveChanges()
{
if(_transaction != null)
{
_transaction.Commit();
this._isCommitted = true;
}
this.EndTransaction();
}
public DataTable RetrieveData(string query, [CallerMemberName] string callerMemberName = "")
{
DataTable dataTable = new DataTable();
try
{
using (SqlCommand command = new SqlCommand())
{
command.Connection = _connection;
command.Transaction = _transaction;
command.CommandText = query;
command.CommandType = CommandType.Text;
using (SqlDataAdapter dataAdapter = new SqlDataAdapter(command))
{
dataAdapter.Fill(dataTable);
}
}
//this.AuditSQL(query, string.Empty);
}
catch (Exception ex)
{
this.AuditSQL(query, ex.Message, callerMemberName);
}
return dataTable;
}
public string RetrieveString(string query, [CallerMemberName] string callerMemberName = "")
{
string text = string.Empty;
try
{
using (SqlCommand oracleCommand = new SqlCommand())
{
oracleCommand.Connection = _connection;
oracleCommand.Transaction = _transaction;
oracleCommand.CommandText = query;
oracleCommand.CommandType = CommandType.Text;
using (SqlDataReader dataReader = oracleCommand.ExecuteReader())
{
dataReader.Read();
text = dataReader.GetValue(0).ToString();
}
}
//this.AuditSQL(query, string.Empty);
}
catch (Exception ex)
{
this.AuditSQL(query, ex.Message, callerMemberName);
}
return text;
}
public bool ExecuteNonQuery(string query, [CallerMemberName] string callerMemberName = "")
{
bool success = false;
try
{
using (SqlCommand command = new SqlCommand())
{
command.Connection = _connection;
command.Transaction = _transaction;
command.CommandText = query;
command.CommandType = CommandType.Text;
command.ExecuteNonQuery();
}
//this.AuditSQL(query, string.Empty);
success = true;
}
catch (Exception ex)
{
this.AuditSQL(query, ex.Message, callerMemberName);
success = false;
}
return success;
}
public bool ExecuteNonQuery(string query, object[] parameters, [CallerMemberName] string callerMemberName = "")
{
bool success = false;
try
{
using (SqlCommand command = new SqlCommand())
{
command.Connection = _connection;
command.Transaction = _transaction;
command.CommandText = query;
command.CommandType = CommandType.Text;
command.Parameters.AddRange(parameters);
command.ExecuteNonQuery();
}
//this.AuditSQL(query, string.Empty);
success = true;
}
catch (Exception ex)
{
this.AuditSQL(query, ex.Message, callerMemberName);
success = false;
}
return success;
}
private void Open()
{
if(_connection.State == ConnectionState.Closed)
{
_connection.Open();
_transaction = _connection.BeginTransaction(_isolationLevel);
}
}
private void Close()
{
if (!this._isCommitted)
{
if (this._transaction != null)
{
this._transaction.Rollback();
}
}
if(this._connection.State == ConnectionState.Open)
{
this._connection.Close();
}
}
private void AuditSQL(string query, string message, string callerMemberName = "")
{
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.AppendLine("**************************************************************************************************");
stringBuilder.AppendLine(string.Format("DATETIME: {0}", DateTime.Now.ToString("MM/dd/yyyy HHmmss")));
stringBuilder.AppendLine(string.Format("SQL: {0}", query));
stringBuilder.AppendLine(string.Format("MESSAGE: {0}", message));
if (!string.IsNullOrWhiteSpace(callerMemberName))
{
stringBuilder.AppendLine(string.Format("METHOD: {0}", callerMemberName));
}
stringBuilder.AppendLine("**************************************************************************************************");
Logger.WriteLineSQL(stringBuilder.ToString()); // Log the query result. Add an #if DEBUG so that live version will no longer log.
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
if (!disposed)
{
if (disposing)
{
if (!this._isCommitted)
{
if (this._transaction != null)
{
this._transaction.Rollback();
}
}
this._transaction.Dispose();
this._connection.Dispose();
}
// Free your own state (unmanaged objects).
// Set large fields to null.
// Free other state (managed objects).
this._transaction = null;
this._connection = null;
disposed = true;
}
}
}
Sample usage:
public void CheckOut(object sender, EventArgs e)
{
string connectionString = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString; // Assuming it is in your web.config
try
{
using(MSSQLDAL dal = new MSSQLDAL(connectionString))
{
dal.BeginTransaction();
string updateQuery = "UPDATE Content SET DateChecked=#DateChecked, CheckedOut=#CheckedOut WHERE MovieID=#MovieID";
SqlParameter uDateChecked = new SqlParameter("DateChecked", SqlDbType.DateTime);
uDateChecked = DateTime.Now;
SqlParameter uCheckedOut = new SqlParameter("CheckedOut", SqlDbType.VarChar);
uCheckedOut = 'Y';
SqlParameter uMovieID = new SqlParameter("MovieID", SqlDbType.Int);
uMovieID = CheckOutList.SelectedValue;
ICollection<SqlParameter> updateParameters = new List<SqlParameter>();
updateParameters.Add(uDateChecked);
updateParameters.Add(uCheckedOut);
updateParameters.Add(uMovieID);
bool updateSuccessful = dal.ExecuteNonQuery(updateQuery, updateParameters.ToArray());
string insertQuery = "INSERT INTO checkout (MovieID, SubscriberID) VALUES (#MovieID, #SubscriberID)";
SqlParameter iSubscriberID = new SqlParameter("SubscriberID", SqlDbType.VarChar);
iSubscriberID = loginName.Text;
SqlParameter iMovieID = new SqlParameter("MovieID", SqlDbType.Int);
iMovieID = CheckOutList.SelectedValue;
ICollection<SqlParameter> insertParameters = new List<SqlParameter>();
insertParameters.Add(iSubscriberID);
insertParameters.Add(iMovieID);
bool insertSuccessful = dal.ExecuteNonQuery(insertQuery, insertParameters.ToArray());
if(updateSuccessful && insertSuccessful)
{
dal.SaveChanges();
lblInfo.Text = "Movie Checked Out";
}
else
{
lblInfo.Text = "Something is wrong with your query!";
}
}
}
catch(Exception ex)
{
StringBuilder sb = new StringBuilder();
sb.AppendLine("Error reading the database.");
sb.AppendLine(ex.Message);
if(ex.InnerException != null)
sb.AppendLine(ex.InnerException.Message);
lblInfo.Text = sb.ToString();
}
}
How can I execute multiple SQL statements in a single command?
You simply need to encapsulate your queries with a BEGIN and END;.
Ex:
BEGIN
SELECT 'A';
SELECT * FROM TableA;
END;
Take note that you need to have ; after your statements. I'd use a StringBuilder to write my long queries if I were you. Also, sending multiple queries as one is only useful if you are not reading any data.
What's the IDAL interface for?
In some of my projects I had to work with different databases. Using the same interface, I am able to create a DAL class for Oracle, MSSql and MySql with very minimal code change. It is also the OOP way. :)

Please change the code like this and try.change the reader.close() after executenonquery().
try
{
connection.Open();
command = new SqlCommand("UPDATE Content SET DateChecked=#DateChecked, CheckedOut=#CheckedOut WHERE MovieID=#MovieID", connection);
command.Parameters.AddWithValue("#DateChecked", DateTime.Now);
command.Parameters.AddWithValue("#CheckedOut", 'Y');
//command.Parameters.AddWithValue("#MovieID",);
command.Parameters.AddWithValue("#MovieID", CheckOutList.SelectedValue);
reader = command.ExecuteReader();
one_data.DataSource = reader;
one_data.DataBind();
command = new SqlCommand("INSERT INTO checkout (MovieID, SubscriberID) VALUES #MovieID, #SubscriberID", connection);
command.Parameters.AddWithValue("#MovieID", CheckOutList.SelectedValue);
command.Parameters.AddWithValue("#SubscriberID", loginName.Text);
command.ExecuteNonQuery();
reader.Close();
}

I finally found an answer after reading all the posts and found that this actually got my INSERT to work
try
{
connection.Open();
command = new SqlCommand("UPDATE Content SET DateChecked=#DateChecked, CheckedOut=#CheckedOut WHERE MovieID=#MovieID", connection);
command.Parameters.AddWithValue("#DateChecked", DateTime.Now);
command.Parameters.AddWithValue("#CheckedOut", 'Y');
//command.Parameters.AddWithValue("#MovieID",);
command.Parameters.AddWithValue("#MovieID", CheckOutList.SelectedValue);
//reader = command.ExecuteReader();
command.ExecuteNonQuery();
one_data.DataSource = reader;
one_data.DataBind();
connection.Close();
connection.Open();
command = new SqlCommand("INSERT INTO checkout (MovieID, SubscriberID) VALUES (#MovieID, #SubscriberID)", connection);
command.Parameters.AddWithValue("#MovieID", CheckOutList.SelectedValue);
command.Parameters.AddWithValue("#SubscriberID", loginName.Text);
command.ExecuteNonQuery();
//reader.Close();
}

Exit out of datareader before else, in if-else statement

I would like to find a way to exit out of datareader after the if statement so that I can execute the insert query in else statement. Is there a way to do it?
I am getting the error that dr is still open and hence cannot perform the below query.
sVendorDetails.VendorID = insertcmd.ExecuteNonQuery();
Here is the code:
public class VendorDetails
{
int _VendorID;
string _VendorName;
public int VendorID
{
set { _VendorID = value; }
get { return _VendorID; }
}
public string VendorName
{
set { _VendorName = value; }
get { return _VendorName; }
}
}
public VendorDetails VendorCheck(string sVendorName)
{
SqlCommand cmd = new SqlCommand("dbo.usp_GetVendorByVendorName", myConnection);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add(new SqlParameter("#VendorName", SqlDbType.VarChar));
cmd.Parameters["#VendorName"].Value = sVendorName;
VendorDetails sVendorDetails = null;
try
{
myConnection.Open();
SqlDataReader dr = cmd.ExecuteReader();
if (dr.HasRows)
{
while (dr.Read())
{
sVendorDetails = new VendorDetails();
sVendorDetails.VendorID = ((int)dr["VendorID"]);
sVendorDetails.VendorName = ((string)dr["VendorName"]).ToUpper().Trim();
}
}
else if (dr.HasRows!= true)
{
ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('VendorName:" + sVendorName + " not found. Inserting Vendor details into Vendor and Invoice table.')", true);
SqlCommand insertcmd = new SqlCommand("dbo.InsertVendorName", myConnection);
insertcmd.CommandType = CommandType.StoredProcedure;
insertcmd.Parameters.Add(new SqlParameter("#VendorName", SqlDbType.VarChar));
insertcmd.Parameters["#VendorName"].Value = sVendorName;
sVendorDetails = new VendorDetails();
sVendorDetails.VendorID = insertcmd.ExecuteNonQuery();
sVendorDetails.VendorName = sVendorName;
}
dr.Close();
return sVendorDetails;
}
catch (SqlException err)
{
throw new ApplicationException("DB usp_GetVendorByVendorName Error: " + err.Message);
}
finally
{
myConnection.Close();
}
}

You will need to close/dispose of your DataReader prior to reusing the connection, as it's still being used.
Maybe something like this?
var readerHasRows = false;
using (var dr = cmd.ExecuteReader())
{
readerHasRows = dr.HasRows;
if(readerHasRows)
{
while (dr.Read())
{
sVendorDetails = new VendorDetails();
sVendorDetails.VendorID = ((int)dr["VendorID"]);
sVendorDetails.VendorName = ((string)dr["VendorName"]).ToUpper().Trim();
}
}
}
if(!readerHasRows)
{
ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('VendorName:" + sVendorName + " not found. Inserting Vendor details into Vendor and Invoice table.')", true);
SqlCommand insertcmd = new SqlCommand("dbo.InsertVendorName", myConnection);
insertcmd.CommandType = CommandType.StoredProcedure;
insertcmd.Parameters.Add(new SqlParameter("#VendorName", SqlDbType.VarChar));
insertcmd.Parameters["#VendorName"].Value = sVendorName;
sVendorDetails = new VendorDetails();
VendorDetails.VendorID = insertcmd.ExecuteNonQuery();
sVendorDetails.VendorName = sVendorName;
}

There are a few things I would like to mention
Your main issue is that you are not closing your DataReader. You can use the using statement for it
You don't need to explicitly open and close the SqlConnection. The SqlCommand object will do it as needed.
You don't need to check with if (dr.HasRows) and then check again in while (dr.Read()). Also, you don't need to loop to pick up only one row of data.
Ideally, I would put the "Fetch" part in a separate function and the "insert" in a separate function, so the functions stay small and reusable.
Your pattern is superfluous if (flag) {TakeAction();} else if (!flag) {TakeAction2();}. Every time the code hits theelse, it will also hit theif (!flag)`
sVendorDetails.VendorID = insertcmd.ExecuteNonQuery(); line looks fishy. If your Stored Procedure returns the VendorId, then you should use ExecuteScalar. Currently it is just storing 1 in all case since you are presumably inserting one row.
Don't discard the original SqlException when creating a custom ApplicationException. Upstream system might want to know more details than you are passing. Pass it along as the InnerException
I have also changed some stylistic aspects:
The variable names changed to the more commonly used camelCase, instead of the incorrectly used Hungarian Notation (sVendorDetails instead of oVendorDetails)
Brace in K&R style
Used var when the right side is a new statement
Use Object Initializers instead of creation+assignment
Below is the code
public VendorDetails VendorCheck(string vendorName, SqlConnection myConnection) {
try {
return GetVendor(vendorName, myConnection) ?? InsertVendor(vendorName, myConnection);
} catch (SqlException err) {
throw new ApplicationException("DB usp_GetVendorByVendorName Error: " + err.Message, err);
}
}
VendorDetails GetVendor(string vendorName, SqlConnection myConnection) {
using (var cmd = new SqlCommand("dbo.usp_GetVendorByVendorName", myConnection)) {
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add(new SqlParameter("#VendorName", SqlDbType.VarChar));
cmd.Parameters["#VendorName"].Value = vendorName;
using (SqlDataReader dr = cmd.ExecuteReader()) {
ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('VendorName:" + vendorName + " not found. Inserting Vendor details into Vendor and Invoice table.')", true); // TODO: Does this really belong here!?!?
if (dr.Read()) {
return new VendorDetails {
VendorID = ((int)dr["VendorID"]),
VendorName = ((string)dr["VendorName"]).ToUpper().Trim()
};
}
}
}
return null;
}
VendorDetails InsertVendor(string vendorName, SqlConnection myConnection) {
using (var insertcmd = new SqlCommand("dbo.InsertVendorName", myConnection)) {
insertcmd.CommandType = CommandType.StoredProcedure;
insertcmd.Parameters.Add(new SqlParameter("#VendorName", SqlDbType.VarChar));
insertcmd.Parameters["#VendorName"].Value = vendorName;
return new VendorDetails {
VendorID = (int)insertcmd.ExecuteScalar(),
VendorName = vendorName
};
}
}

passing a string to a class

I have a problem with my SQL datareader, i want to make an external class and make the code in my xaml.cs as short as possible, because there are a lot of sqldatareaders needed in my program. for this I want to pass following two strings to the datareader class:
public void refreshcombobox()
{
cbGebruiker.Items.Clear();
database = new DataBase();
string sqlrdr = "(rdr.GetString(1).ToString().Trim())";
List<string> reader = database.ReaderRdr("Select * from Gebruikers", ref sqlrdr);
foreach (String str in reader)
{
cbGebruiker.Items.Add(str);
}
}
however, when I do this this is the result in my program instead of the actual results that are stored in the database:
http://i58.tinypic.com/301j2vo.jpg (I can't post images)
can somebody help me with this? I've searched everywhere...
I don't know how to pass the rdr.GetString(1).ToString().Trim() to make it actually look stuff up in the db. Instead of just copying the string directly into the list.
This is the class:
namespace ClassLib
{
public class DataBase
{
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["kassadatabase"].ConnectionString);
public object ScalarObject(string sql)
{
object value = null;
try
{
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
value = cmd.ExecuteScalar();
}
catch (SqlException ex)
{
MessageBox.Show(ex.Message);
}
finally
{
if (conn != null) conn.Close();
}
return value;
}
public List<string> ReaderRdr(string sql)
{
SqlDataReader rdr = null;
List<string> reader = new List<string>();
try
{
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
rdr = cmd.ExecuteReader();
while (rdr.Read())
{
//reader.Add(rdr.GetString(1).ToString().Trim());
}
}
catch (SqlException ex)
{
MessageBox.Show(ex.Message);
}
finally
{
if (rdr != null) rdr.Close();
if (conn != null) conn.Close();
}
return reader;
}
//public List<string> ReaderRdr(string sql, ref string str)
//{
// SqlDataReader rdr = null;
// List<string> reader = new List<string>();
// try
// {
// conn.Open();
// SqlCommand cmd = new SqlCommand(sql, conn);
// rdr = cmd.ExecuteReader();
// while (rdr.Read())
// {
// //MessageBox.Show(str.ToString());
// //var strRdr = str;
// //MessageBox.Show(strRdr.ToString());
// //reader.Add(rdr.GetString(1).ToString().Trim());
// reader.Add(str);
// Console.WriteLine(String.Format("{0}", rdr[0]));
// }
// }
// catch (SqlException ex)
// {
// MessageBox.Show(ex.Message);
// }
// finally
// {
// if (rdr != null) rdr.Close();
// if (conn != null) conn.Close();
// }
// return reader;
//}
public void ExecuteNQuery(string insertString)
{
try
{
conn.Open();
SqlCommand cmd2 = new SqlCommand(insertString, conn);
cmd2.ExecuteNonQuery();
}
catch (SqlException ex)
{
MessageBox.Show(ex.Message);
}
finally
{
if (conn != null) conn.Close();
}
}
}
}
public List<string> ReaderRdr(string sql)
{
SqlDataReader rdr = null;
List<string> reader = new List<string>();
try
{
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
rdr = cmd.ExecuteReader();
while (rdr.Read())
{
//reader.Add(rdr.GetString(1).ToString().Trim());
}
.....
now in the methode public list i want to replace the //reader.Add(rdr.GetString(1).ToString().Trim()); part(wich works fine)
with a string that is passed to the method.
public List<string> ReaderRdr(string sql, string strRdr)
{
SqlDataReader rdr = null;
List<string> reader = new List<string>();
try
{
conn.Open();
SqlCommand cmd = new SqlCommand(sql, conn);
rdr = cmd.ExecuteReader();
while (rdr.Read())
{
//reader.Add(strRdr);
}

I'm not 100% sure what you're trying to do, but I can tell you right now that this is what you're doing wrong - the string (str) you're passing to ReaderRdr is just a string literal of C# code. There's super hacky (super inadvisable) things you can do to mimic what exists in other languages as eval(), but there's no built-in way to do that in C#. Nothing (sensible) you do to "(rdr.GetString(1).ToString().Trim())" is ever going to get a string, or cast it to string, or trim anything.
Within your ReaderRdr function, all you're accomplishing is just to add the string str to your List<string> reader. This accomplishes nothing and has no bearing whatsoever on the results you get from your database query in your SqlDataReader rdr. If you want to store the data you actually get from your database, use rdr, not the (useless) string argument str.
Also, I feel like you must have left something out of your code - you're instantiating your SqlCommand cmd with conn as your second argument, but I don't see that defined anywhere within your ReaderRdr method, and it's not an argument passed to ReaderRdr. You don't have an SqlConnection object as a field or property within your class, do you?
As far as what you should maybe do, despite lacking much of any context in terms of your actual aims - if you want to get any given column of the result for each row returned by your SqlDataReader:
rdr = cmd.ExecuteReader();
while (rdr.Read())
{
var yourDataCell = rdr[yourColumnIndex];
// or:
var yourDataCellOtherWay = rdr["YourColumnName"];
}
Alternately, you can just iterate through each of the cells in any given row produced by your SqlDataReader like so:
for(int i = 0 ; i < numberOfColumns; i++) {
// do something with rdr[i] here
}
I'm not sure if there's anything you can do establish numberOfColumns based on the state of your SqlDataReader, but others might know better.

You actually adding the String that you passed to a function to your reader reader.Add(str); You get the response from SQL I your rdr.
This item will show you something from your database:
Console.WriteLine(String.Format("{0}", rdr[0]));