Develop Reference

I'm having a problem with MySql in C# .Net Framework

I'm migrating from Access to MySql. When "btn_Ekle" is clicked, the shelf is added to the database, but the codes written afterwards do not work.
Also, RafListesi() works at first, but when we close the Add Shelves window after adding a shelf and then open it again, the shelfs are not listed. It is listed after reopening the program.
public static ClassRaf RafEkle(string ad)
{
ClassRaf result;
try
{
if (ClassData.RafSec(ad) != null)
{
MessageBox.Show("Eklemek İstediğiniz Raf Zaten Kayıtlarda Mevcut.", "Kütüphane Sistemi | Bilgi", MessageBoxButtons.OK, MessageBoxIcon.Information);
result = null;
}
else
{
MySqlCommand sqlCommand = new MySqlCommand("INSERT INTO bookrack (shelf_name) VALUES (#shelf_name)", ClassData.connectSql);
sqlCommand.Parameters.Add("#shelf_name", MySqlDbType.VarChar).Value = ad;
if (sqlCommand.ExecuteNonQuery() > 0)
{
MySqlCommand sqlCommand1 = new MySqlCommand("SELECT * FROM bookrack ORDER BY id DESC", ClassData.connectSql);
MySqlDataReader sqlDataReader = sqlCommand1.ExecuteReader();
if (sqlDataReader.Read())
{
result = ClassData.RafSec((int)sqlDataReader["id"]);
}
else
{
result = null;
}
}
else
{
result = null;
}
}
}
catch
{ result = null; }
return result;
}
private void btnEkle_Click(object sender, EventArgs e)
{
ClassRaf classRaf = ClassData.RafEkle(txtEkle.Text);
if (classRaf != null)
{
txtEkle.Text = "";
liste.Items.Add(classRaf.Ad);
ClassLog.Log(string.Concat(new object[]
{
classRaf.Ad,
" adlı raf eklendi. ID=[",
classRaf.ID,
"]"
}));
ShelfValid();
txtEkle.Select();
}
}
public static List<ClassRaf> RafListesi()
{
List<ClassRaf> result;
try
{
List<ClassRaf> list = new List<ClassRaf>();
MySqlCommand sqlCommand = new MySqlCommand("SELECT * FROM bookrack", ClassData.connectSql);
MySqlDataReader sqlDataReader = sqlCommand.ExecuteReader();
while (sqlDataReader.Read())
{
list.Add(new ClassRaf
{
ID = Convert.ToInt32(sqlDataReader["id"]),
Ad = sqlDataReader["shelf_name"].ToString()
});
}
result = list;
sqlDataReader.Close();
sqlDataReader.Dispose();
}
catch
{ result = new List<ClassRaf>(); }
return result;
}
public static ClassRaf RafEkle(string ad) - (Add Shelf)
private void btnEkle_Click
private void btnEkle_Click(object sender, EventArgs e)

System.ArgumentException Value does not fall within the expected range, SQL issue

I'm using .Net Compact 3.5 Windows 7 CE.
I have an application with about 50 users, I have it setup so that I would get an email every time a database transaction failed, with the query.
Every so often I would get an email with a stack trace that starts like this:
System.ArgumentException: Value does not fall within the expected range.
at System.Data.SqlClient.SqlParameterCollection.Validate(Int32 index, SqlParameter value)
at System.Data.SqlClient.SqlParameterCollection.AddWithoutEvents(SqlParameter value)
at System.Data.SqlClient.SqlParameterCollection.Add(SqlParameter value)
at MedWMS.Database.startSqlConnection(String query, SqlParameter[] parameters, SqlConnection connection, SqlCommand cmd)
at MedWMS.Database.<>c__DisplayClasse.b__8()
at MedWMS.Database.retry(Action action)
at MedWMS.Database.executeNonQuery(String query, SqlParameter[] parameters, String connectionString)...
The SQL query which causes this issue is not always the same. I run the same query seconds after I get the email in SQL Server Management Studio with no issues.
I would like to know why this could be happening. This is my first question on SO so please let me know if I'm doing something wrong. I would be happy to answer any questions to provide more detail.
This is a sample of the code that would cause this error:
SqlParameter[] parameters = new SqlParameter[1];
parameters[0] = new SqlParameter("#salesOrder", this.salesOrderNumber);
string query = #"
Select InvTermsOverride from SorMaster where SalesOrder = Convert(int, #salesOrder) and InvTermsOverride = '07' --07 is for COD";
DataTable dt = Database.executeSelectQuery(query, parameters, Country.getCurrent().getSysproConnectionStrReportServer());
This is the query that actually gets passed:
Select InvTermsOverride from SorMaster where SalesOrder = Convert(int, '000000001138325') and InvTermsOverride = '07' --07 is for COD
Here is the relevant methods from the Database class:
public static DataTable executeSelectQuery(String query, SqlParameter[] parameters, string connectionString)
{
DataTable dt = new DataTable();
using (SqlConnection connection = new SqlConnection(connectionString))
{
SqlCommand cmd = null;
try
{
retry(() =>
{
cmd = startSqlConnection(query, parameters, connection, cmd);
using (SqlDataReader reader = cmd.ExecuteReader())
{
dt.Load(reader);
}
});
}
catch (Exception ex)
{
onDbConnectionCatch(cmd, ex);
}
finally
{
cmd.Dispose();
connection.Close();
}
}
return dt;
}
public static void executeNonQuery(String query, SqlParameter[] parameters, string connectionString)
{
using (SqlConnection connection = new SqlConnection(connectionString))
{
SqlCommand cmd = null;
try
{
retry(() =>
{
cmd = startSqlConnection(query, parameters, connection, cmd);
cmd.ExecuteNonQuery();
});
}
catch (Exception ex)
{
onDbConnectionCatch(cmd, ex);
}
finally
{
cmd.Dispose();
connection.Close();
}
}
}
private static void retry(Action action)
{
int retryCount = 3;
int retryInterval = 1000;
Exception lastException = null;
for (int retry = 0; retry < retryCount; retry++)
{
try
{
if (retry > 0)
System.Threading.Thread.Sleep(retryInterval);
action();
lastException = null;
return;
}
catch (Exception ex)
{
lastException = ex;
}
}
if (lastException != null)
{
throw lastException;
}
}
private static SqlCommand startSqlConnection(String query, SqlParameter[] parameters, SqlConnection connection, SqlCommand cmd)
{
if (connection.State != ConnectionState.Open)
{
connection.Open();
}
cmd = new SqlCommand(query, connection);
if (parameters != null)
{
foreach (SqlParameter sp in parameters)
{
if (sp != null)
{
cmd.Parameters.Add(sp);
}
}
}
return cmd;
}
private static void onDbConnectionCatch(SqlCommand cmd, Exception ex)
{
try
{
new BigButtonMessageBox("", "Unable connect to database").ShowDialog();
sendEmailWithSqlQuery(cmd, ex);
}
catch
{
}
}
private static void sendEmailWithSqlQuery(SqlCommand cmd, Exception ex)
{
string query2 = "cmd was null";
if (cmd != null)
{
query2 = cmd.CommandText;
foreach (SqlParameter p in cmd.Parameters)
{
query2 = query2.Replace(p.ParameterName, "'" + p.Value.ToString() + "'");
}
}
InternetTools.sendEmail("DB ERROR", ex.ToString() + "\r\n" + query2);
}

I had the same issue as Can't solve "Sqlparameter is already contained by another SqlparameterCollection"
For some reason SQL CE has a different error.
Because of my retry method, I couldn't reuse the SqlParameter object, still not sure why it's not allowed
Anyways I changed
cmd.Parameters.Add(sp);
to
cmd.Parameters.Add(sp.ParameterName, sp.Value);

Have trouble reading a null returned from stored procedure

I have a stored procedure that returns a single record, either null or data if present.
In my code I need to check what that procedure returns. What is the right way to do it?
Now when, running the code I have an exception saying: "Invalid attempt to read when no data is present." I'm using Visual Studio 2005.
Here is my method:
public static String GetRegionBasedOnIso(String isoNum)
{
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConn"].ConnectionString);
String region = null;
try
{
using (SqlCommand cmd = new SqlCommand("MyProc", conn))
{
conn.Open();
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#isoNum", isoNum);
using (SqlDataReader dr = cmd.ExecuteReader())
{
if (dr.IsDBNull(0))
{
return null;
}
else
{
region = (String)dr["region"];
}
}
}
}
catch (Exception e)
{
throw new System.Exception(e.Message.ToString());
}
finally
{
conn.Close();
}
return region;
}
What can I do to fix it? Thank you

if (dr.Read())
{
if (dr.IsDBNull(0))
{
return null;
}
else
{
region = (String)dr["region"];
}
}
else
{
// do something else as the result set is empty
}

The connection is open

A few months ago I made a test program for a project and everything worked fine there.
Now I am working on the program itself, so I copied the code from the test program and
changed the the names of the columns,buttons etc. so it would fit the current program.
When I try to add something into the database it does nothing on the first click, on the
second pops up an error which says that the connection is open.. I really got no idea what's
the problem. I tried to check again if I made a mistake in a column name or the database name
but everything seems to be correct.
Note: I also have a function that show data from the database and it works without any problem.
private void InsertData()
{
string NewCode = GenerateCode();
string NewSentence = txtSentence.Text;
string NewRow = NewRowNum();
try
{
string AddData = "INSERT INTO ShopSentences (BinaryStrings,Sentence,RowNumber) VALUES (#NewBinaryString,#NewSentence,#NewRowNumber)";
SqlCommand DataAdd = new SqlCommand(AddData, Connection);
DataAdd.Parameters.AddWithValue("#NewBinaryString", NewCode);
DataAdd.Parameters.AddWithValue("#NewNewSentence", NewSentence);
DataAdd.Parameters.AddWithValue("#NewRowNumber", NewRow);
Connection.Open();
DataAdd.ExecuteNonQuery();
Connection.Close();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
//Checking the banary code in the last row
string GenerateCode()
{
string RowNo = RowFind();
int Row = int.Parse(RowNo);
int Code = Row + 1;
string Cd = Convert.ToString(Code, 2);
int Ln = Cd.Trim().Length;
if (Ln == 3)
{
Cd = "100" + Cd;
}
else if (Ln == 4)
{
Cd = "10" + Cd;
}
else if (Ln == 5)
{
Cd = "1" + Cd;
}
return Cd;
}
//Finding the last row
string RowFind()
{
Connection.Open();
string queryString = string.Format("SELECT * FROM ShopSentences");
SqlDataAdapter sda = new SqlDataAdapter(queryString, Connection);
DataTable dt = new DataTable("ShopSentences");
sda.Fill(dt);
Connection.Close();
return dt.Rows[dt.Rows.Count - 1]["RowNumber"].ToString();
}
string NewRowNum()
{
string Row = RowFind();
int CalcRow = int.Parse(Row) + 1;
Row = CalcRow.ToString();
return Row;
}
The connection that appears to be open is the one in the string RowFind().
Here are the other related things to the database:
public partial class frmShop : Form
{
System.Data.SqlClient.SqlConnection Connection;
public frmShop()
{
string DatabaseConnection = WindowsFormsApplication1.Properties.Settings.Default.BinaryStringsDictionaryConnectionString1;
Connection = new System.Data.SqlClient.SqlConnection();
Connection.ConnectionString = DatabaseConnection;
InitializeComponent();
}
private void frmShop_Load(object sender, EventArgs e)
{
// TODO: This line of code loads data into the 'binaryStringsDictionaryDataSet.ShopSentences' table. You can move, or remove it, as needed.
this.shopSentencesTableAdapter.Fill(this.binaryStringsDictionaryDataSet.ShopSentences);
}
private void GetSentence()
{
try
{
Connection.Open();
SqlDataReader ReadSentence = null;
Int32 BinaryInt = Int32.Parse(txtBinaryString.Text);
string CommandString = "SELECT Sentence FROM ShopSentences WHERE BinaryStrings = #BinaryString";
SqlCommand Command = new SqlCommand(CommandString, Connection);
Command.Parameters.Add("#BinaryString", System.Data.SqlDbType.Int).Value = BinaryInt;
ReadSentence = Command.ExecuteReader();
while (ReadSentence.Read())
{
txtSentence.Text = (ReadSentence["Sentence"].ToString());
Fit = 1;
}
Connection.Close();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
}

You are getting errors because you are reusing the same connection Connection.Open(); several times.
Your method InsertData() is doing this 3 times in the same method.
You should create a new instance of the connection object and dispose it on your methods.
Using Statement are the way to go.
private void InsertData()
{
using (var Connection = new SqlConnection(DatabaseConnection))
{
string NewCode = GenerateCode();
string NewSentence = txtSentence.Text;
string NewRow = NewRowNum();
try
{
Connection.Open();
string AddData = "INSERT INTO ShopSentences (BinaryStrings,Sentence,RowNumber) VALUES (#NewBinaryString,#NewSentence,#NewRowNumber)";
SqlCommand DataAdd = new SqlCommand(AddData, Connection);
DataAdd.Parameters.AddWithValue("#NewBinaryString", NewCode);
DataAdd.Parameters.AddWithValue("#NewNewSentence", NewSentence);
DataAdd.Parameters.AddWithValue("#NewRowNumber", NewRow);
DataAdd.ExecuteNonQuery();
//Connection.Close(); no need to close
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
}
You can save one more connection if you store the row returned by RowFind()
string RowFind()
{
using (var Connection = new SqlConnection(DatabaseConnection))
{
Connection.Open();
string queryString = string.Format("SELECT * FROM ShopSentences");
SqlDataAdapter sda = new SqlDataAdapter(queryString, Connection);
DataTable dt = new DataTable("ShopSentences");
sda.Fill(dt);
//Connection.Close();
return dt.Rows[dt.Rows.Count - 1]["RowNumber"].ToString();
}
}
So you would connect once instead of twice:
var Row = RowFind();
string NewCode = GenerateCode(Row);
string NewRow = NewRowNum(Row);
string NewSentence = txtSentence.Text;
Declare your connection string variable to a property so you can reuse it:
private string DatabaseConnection {get; set;}

Instead using an instance level SqlConnection you should only provide a common factory for creating a connection:
public partial class frmShop : Form
{
private string ConnectionString
{
get { return WindowsFormsApplication1.Properties.Settings.Default.BinaryStringsDictionaryConnectionString1; }
}
public frmShop()
{
InitializeComponent();
}
private SqlConnection CreateConnection()
{
var conn = new SqlConnection(ConnectionString);
conn.Open();
return conn;
}
private void frmShop_Load(object sender, EventArgs e)
{
// TODO: This line of code loads data into the 'binaryStringsDictionaryDataSet.ShopSentences' table. You can move, or remove it, as needed.
this.shopSentencesTableAdapter.Fill(this.binaryStringsDictionaryDataSet.ShopSentences);
}
private void GetSentence()
{
try
{
using (var conn = CreateConnection())
{
var BinaryInt = int.Parse(txtBinaryString.Text);
var commandString = "SELECT Sentence FROM ShopSentences WHERE BinaryStrings = #BinaryString";
using (var Command = new SqlCommand(commandString, conn))
{
Command.Parameters.Add("#BinaryString", System.Data.SqlDbType.Int).Value = BinaryInt;
using (var readSentence = Command.ExecuteReader())
{
while (readSentence.Read())
{
txtSentence.Text = (readSentence["Sentence"].ToString());
Fit = 1;
}
}
}
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private void InsertData()
{
try
{
using (var conn = CreateConnection())
{
var commandString = "INSERT INTO ShopSentences (BinaryStrings,Sentence,RowNumber) VALUES (#NewBinaryString,#NewSentence,#NewRowNumber)";
using (var comm = new SqlCommand(commandString, conn))
{
comm.Parameters.AddWithValue("#NewBinaryString", GenerateCode());
comm.Parameters.AddWithValue("#NewNewSentence", txtSentence.Text);
comm.Parameters.AddWithValue("#NewRowNumber", NewRowNum());
comm.ExecuteNonQuery();
}
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
//Checking the banary code in the last row
string GenerateCode()
{
string RowNo = RowFind();
int Row = int.Parse(RowNo);
int Code = Row + 1;
string Cd = Convert.ToString(Code, 2);
int Ln = Cd.Trim().Length;
if (Ln == 3)
{
Cd = "100" + Cd;
}
else if (Ln == 4)
{
Cd = "10" + Cd;
}
else if (Ln == 5)
{
Cd = "1" + Cd;
}
return Cd;
}
//Finding the last row
string RowFind()
{
using (var conn = CreateConnection())
{
var commandString = "SELECT * FROM ShopSentences";
using (var comm = new SqlCommand(commandString, conn))
{
using (var sda = new SqlDataAdapter(queryString, Connection))
{
using (DataTable dt = new DataTable("ShopSentences"))
{
sda.Fill(dt);
return dt.Rows[dt.Rows.Count - 1]["RowNumber"].ToString();
}
}
}
}
}
string NewRowNum()
{
var Row = RowFind();
var CalcRow = int.Parse(Row) + 1;
return CalcRow.ToString();
}
}
But this is just the beginning you should not have any hard SQL dependency in your Form classes.

When sharing same SqlConnection instance several times in your code, instead of directly opening the you can rather check the connection state first and then open it if not already opened. For example:
if(Connection.State!= ConnectionState.Open)
Connection.Open();

C# data reader does not retrieve the data

I am trying to load data into a textbox by using a DataReader depend on the Drop down list selection. Didn't get error from this code, but the data is not loaded into textbox. please correct me.
public void text()
{
cn1.Open();
string s;
s = "select Request_Type from component where Material_Code='" + Mcodeddl.SelectedItem.Text + "' ";
SqlCommand cd1 = new SqlCommand(s, cn1);
SqlDataReader rd;
try
{
rd = cd1.ExecuteReader();
while (rd.Read())
{
TextBox4.Text = rd["Request_Type"].ToString().Trim();
}
rd.Close();
}
catch (Exception e)
{
Response.Write(e.Message);
}
finally
{
cd1.Dispose();
cn1.Close();
}
}
public void MC()
{
Mcodeddl.Items.Clear();
ListItem li1 = new ListItem();
li1.Text = "-Select-";
Mcodeddl.Items.Add(li1);
Mcodeddl.SelectedIndex = 0;
cn1.Open();
string s1;
s1 = "select Material_Code from component";
SqlCommand cd1 = new SqlCommand(s1, cn1);
SqlDataReader dr1;
try
{
dr1 = cd1.ExecuteReader();
while (dr1.Read())
{
ListItem ni1 = new ListItem();
ni1.Text = dr1["Material_Code"].ToString().Trim();
Mcodeddl.Items.Add(ni1);
}
dr1.Close();
}
catch (Exception e)
{
Response.Write(e.Message);
}
finally
{
cd1.Dispose();
cn1.Close();
}
}

If everything works fine without exceptions that is mean the connection established correctly and the SQL command is correct. I think you have to make sure about your SQL statement. Maybe it returns nothing because there are no matches.
We need more explain about your issue.