The connection is open

The connection is open - c#

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();

Related

Load data from database to string

I'm trying at the moment to get an information from a database and want to save it in a string, but yeah not sure about how really to do it right.
This is my code, where I open the LoadSql function:
public void LoadData(string KNR, string WNR, String filter)
{
// WHERE
const string sqlTemplate = "SELECT KUNDENAUFTRAGSNR FROM MESSFELD.AUSSTANDSDATEN WHERE FTNR = '" + txt_Barcode_read.Text + "'";
string sql = string.Format(sqlTemplate, filter);
Database cdb = new Database();
// try to connect and cancel on error
if (!cdb.Open("**********", "*********"))
{
SetStatusText("Datenbank ist nicht verfügbar.");
return;
}
WNR = cdb.LoadSql(sql);
cdb.Close();
}
And here is the LoadSQL function:
public DataTable LoadSql(string sql)
{
try
{
OracleCommand command = new OracleCommand(sql, _con);
command.InitialLONGFetchSize = -1;
OracleDataReader rdr = command.ExecuteReader();
DataTable dt = new DataTable();
dt.Load(rdr);
return dt;
}
catch
{
return null;
}
}
For the moment the LoadSQL is saving in datatable, how to change for saving the number in the string WNR?

You can re-write your LoadSQL function to something like this :
public string LoadSql(string sql)
{
try
{
OracleCommand command = new OracleCommand(sql, _con);
command.InitialLONGFetchSize = -1;
OracleDataReader rdr = command.ExecuteReader();
rdr.Read();
if(rdr.HasRows)
return rdr.GetString(0);
else
return "";
}
catch
{
return null;
}
}

How To insert data into SQL Sever with C# without using the database wizard(visual studio)

I'm having trouble inserting data into my table called "client" in my database called "vet".
I'm trying to do the connection manually as opposed to using the database wizard. I want to do it this way so that i can hide the majority of my code in a separate class.
I have a feeling I have the logic for this all wrong as I'm not making use of a data set, I was hoping someone could point me in the right direction.
This is for a school assignment and not for real world use. I have read a number of similar posts but am still unable to come to a solution.
public void CommitToDatabase()
{
using (var con = new SqlConnection(CLSDatabaseDetails.GlobalConnectionString))
{
DataTable client = new DataTable();
DataSet ds = new DataSet();
string commandString = "SELECT * FROM client";
SqlCommand cmd = new SqlCommand(commandString, con);
con.Open();
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(client);
DataRow newClientRow = ds.Tables["client"].NewRow();
newClientRow["ClientID"] = ClientID;
newClientRow["FirstName"] = FirstName;
newClientRow["LastName"] = LastName;
newClientRow["Phone"] = PhoneNumber;
newClientRow["CAddress"] = Address;
newClientRow["Email"] = Email;
newClientRow["CUsername"] = Username;
newClientRow["CPassword"] = Password;
client.Rows.Add(newClientRow);
da.Update(client);
}
}

A DataSet is a collection of DataTables. In your example, you're only referring to one table. The SqlDataAdapter.Fill method will populate either DataSet or DataTable. You're calling da.Fill(client) which is fine - it will fill the DataTable client. You could also call da.Fill(ds, "client") which will fill the DataSet ds. You can then extract your table via ds.Tables["client"]. Using a DataSet in this example is overkill, but you can show your tutor how a DataSet works.
You're filling the DataTable but then adding the new row with reference to the DataSet. But in your example, the DataSet ds has nothing in it, because you filled the DataTable not the DataSet. Try this:
DataSet ds = new DataSet();
string commandString = "SELECT TOP 0 * FROM client";
SqlCommand cmd = new SqlCommand(commandString, con);
con.Open();
SqlDataAdapter da = new SqlDataAdapter(cmd);
SqlCommandBuilder builder = new SqlCommandBuilder(da);
da.Fill(ds, "client");
DataTable client = ds.Tables["client"];
DataRow newClientRow = client.NewRow();
... ... ...
client.Rows.Add(newClientRow);
builder.GetInsertCommand();
da.Update(client);
If you only want to insert a row, you don't need to SELECT all the rows. If you SELECT TOP 0 * from client you'll get the column names (which you need) but without the overhead of returning all the rows.

Try something like this:
public void CommitToDatabase()
{
using (var con = new SqlConnection(CLSDatabaseDetails.GlobalConnectionString))
{
DataTable client = new DataTable();
string commandString = "SELECT * FROM client";
SqlCommand cmd = new SqlCommand(commandString, con);
con.Open();
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(client);
DataRow newClientRow = client.NewRow();
newClientRow["ClientID"] = ClientID;
newClientRow["FirstName"] = FirstName;
newClientRow["LastName"] = LastName;
newClientRow["Phone"] = PhoneNumber;
newClientRow["CAddress"] = Address;
newClientRow["Email"] = Email;
newClientRow["CUsername"] = Username;
newClientRow["CPassword"] = Password;
client.Rows.Add(newClientRow);
da.Update(client);
}
}

I can't tell what the source of your data is. Anyway, here are two examples of moving data from a CSV file to SQL Server and from a DataGridView to SQL Server.
using Microsoft.VisualBasic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.Data.SqlClient;
using System.IO;
using Microsoft.VisualBasic.FileIO;
using System.Data.Odbc;
using System.Data.OleDb;
using System.Configuration;
public class Form1
{
private void Button1_Click(System.Object sender, System.EventArgs e)
{
dynamic headers = (from header in DataGridView1.Columns.Cast<DataGridViewColumn>()header.HeaderText).ToArray;
dynamic rows = from row in DataGridView1.Rows.Cast<DataGridViewRow>()where !row.IsNewRowArray.ConvertAll(row.Cells.Cast<DataGridViewCell>.ToArray, c => c.Value != null ? c.Value.ToString : "");
string str = "";
using (IO.StreamWriter sw = new IO.StreamWriter("C:\\Users\\Excel\\Desktop\\OrdersTest.csv")) {
sw.WriteLine(string.Join(",", headers));
//sw.WriteLine(String.Join(","))
foreach (void r_loopVariable in rows) {
r = r_loopVariable;
sw.WriteLine(string.Join(",", r));
}
sw.Close();
}
}
private void Button2_Click(System.Object sender, System.EventArgs e)
{
//Dim m_strConnection As String = "server='Server_Name';Initial Catalog='Database_Name';Trusted_Connection=True;"
//Catch ex As Exception
// MessageBox.Show(ex.ToString())
//End Try
//Dim objDataset1 As DataSet()
//Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
//Dim da As OdbcDataAdapter
System.Windows.Forms.OpenFileDialog OpenFile = new System.Windows.Forms.OpenFileDialog();
// Does something w/ the OpenFileDialog
string strFullPath = null;
string strFileName = null;
TextBox tbFile = new TextBox();
// Sets some OpenFileDialog box options
OpenFile.Filter = "CSV Files (*.csv)|*.csv|All files (*.*)|*.*";
// Shows only .csv files
OpenFile.Title = "Browse to file:";
// Title at the top of the dialog box
// Makes the open file dialog box show up
if (OpenFile.ShowDialog() == DialogResult.OK) {
strFullPath = OpenFile.FileName;
// Assigns variable
strFileName = Path.GetFileName(strFullPath);
// Checks to see if they've picked a file
if (OpenFile.FileNames.Length > 0) {
tbFile.Text = strFullPath;
// Puts the filename in the textbox
// The connection string for reading into data connection form
string connStr = null;
connStr = "Driver={Microsoft Text Driver (*.txt; *.csv)}; Dbq=" + Path.GetDirectoryName(strFullPath) + "; Extensions=csv,txt ";
// Sets up the data set and gets stuff from .csv file
OdbcConnection Conn = new OdbcConnection(connStr);
DataSet ds = default(DataSet);
OdbcDataAdapter DataAdapter = new OdbcDataAdapter("SELECT * FROM [" + strFileName + "]", Conn);
ds = new DataSet();
try {
DataAdapter.Fill(ds, strFileName);
// Fills data grid..
DataGridView1.DataSource = ds.Tables(strFileName);
// ..according to data source
// Catch and display database errors
} catch (OdbcException ex) {
OdbcError odbcError = default(OdbcError);
foreach ( odbcError in ex.Errors) {
MessageBox.Show(ex.Message);
}
}
// Cleanup
OpenFile.Dispose();
Conn.Dispose();
DataAdapter.Dispose();
ds.Dispose();
}
}
}
private void Button3_Click(System.Object sender, System.EventArgs e)
{
SqlConnection cnn = default(SqlConnection);
string connectionString = null;
string sql = null;
connectionString = "data source='Server_Name';" + "initial catalog='Database_Name';Trusted_Connection=True";
cnn = new SqlConnection(connectionString);
cnn.Open();
sql = "SELECT * FROM [Order Details]";
SqlDataAdapter dscmd = new SqlDataAdapter(sql, cnn);
DataSet ds = new DataSet();
dscmd.Fill(ds);
DataGridView1.DataSource = ds.Tables(0);
cnn.Close();
}
private void ProductsDataGridView_CellFormatting(object sender, System.Windows.Forms.DataGridViewCellFormattingEventArgs e)
{
if (e.ColumnIndex == DataGridView1.Columns(3).Index && e.Value != null) {
//
if (Convert.ToInt32(e.Value) < 10) {
e.CellStyle.BackColor = Color.OrangeRed;
e.CellStyle.ForeColor = Color.LightGoldenrodYellow;
}
//
}
//
}
//Private Sub ProductsDataGridView_CellFormatting(ByVal sender As Object, _
// ByVal e As System.Windows.Forms.DataGridViewCellFormattingEventArgs) _
// Handles DataGridView1.CellFormatting
// '
// If e.ColumnIndex = DataGridView1.Columns("DataGridViewTextBoxColumn8").Index _
// AndAlso e.Value IsNot Nothing Then
// '
// If CInt(e.Value) < 5 Then
// e.CellStyle.BackColor = Color.OrangeRed
// e.CellStyle.ForeColor = Color.LightGoldenrodYellow
// End If
// '
// End If
// '
//End Sub
//If e.ColumnIndex = ProductsDataGridView.Columns(4).Index _
//AndAlso e.Value IsNot Nothing Then
//'
// If CInt(e.Value) = 0 Then
// e.CellStyle.BackColor = Color.OrangeRed
// e.CellStyle.ForeColor = Color.LightGoldenrodYellow
// End If
//End If
// ''To (you need to change the column name)
// If e.ColumnIndex = ProductsDataGridView.Columns("YourColumnName").Index _
// AndAlso e.Value IsNot Nothing Then
//'
// If CInt(e.Value) = 0 Then
// e.CellStyle.BackColor = Color.OrangeRed
// e.CellStyle.ForeColor = Color.LightGoldenrodYellow
// End If
//End If
private void Button4_Click(System.Object sender, System.EventArgs e)
{
DataTable tblReadCSV = new DataTable();
tblReadCSV.Columns.Add("FName");
tblReadCSV.Columns.Add("LName");
tblReadCSV.Columns.Add("Department");
TextFieldParser csvParser = new TextFieldParser("C:\\Users\\Excel\\Desktop\\Employee.txt");
csvParser.Delimiters = new string[] { "," };
csvParser.TrimWhiteSpace = true;
csvParser.ReadLine();
while (!(csvParser.EndOfData == true)) {
tblReadCSV.Rows.Add(csvParser.ReadFields());
}
SqlConnection con = new SqlConnection("Server='Server_Name';Database='Database_Name';Trusted_Connection=True;");
string strSql = "Insert into Employee(FName,LName,Department) values(#Fname,#Lname,#Department)";
//Dim con As New SqlConnection(strCon)
SqlCommand cmd = new SqlCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = strSql;
cmd.Connection = con;
cmd.Parameters.Add("#Fname", SqlDbType.VarChar, 50, "FName");
cmd.Parameters.Add("#Lname", SqlDbType.VarChar, 50, "LName");
cmd.Parameters.Add("#Department", SqlDbType.VarChar, 50, "Department");
SqlDataAdapter dAdapter = new SqlDataAdapter();
dAdapter.InsertCommand = cmd;
int result = dAdapter.Update(tblReadCSV);
}
private void Button5_Click(System.Object sender, System.EventArgs e)
{
string SQLConnectionString = "Data Source=Excel-PC\\SQLEXPRESS;" + "Initial Catalog=Northwind;" + "Trusted_Connection=True";
// Open a connection to the AdventureWorks database.
using (SqlConnection SourceConnection = new SqlConnection(SQLConnectionString)) {
SourceConnection.Open();
// Perform an initial count on the destination table.
SqlCommand CommandRowCount = new SqlCommand("SELECT COUNT(*) FROM dbo.Orders;", SourceConnection);
long CountStart = System.Convert.ToInt32(CommandRowCount.ExecuteScalar());
Console.WriteLine("Starting row count = {0}", CountStart);
// Get data from the source table as a AccessDataReader.
//Dim ConnectionString As String = "Provider=Microsoft.Jet.OLEDB.4.0;" & _
// "Data Source=" & "C:\Users\Excel\Desktop\OrdersTest.txt" & ";" & _
// "Extended Properties=" & "text;HDR=Yes;FMT=Delimited"","";"
string ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + "C:\\Users\\Excel\\Desktop\\" + ";" + "Extended Properties=\"Text;HDR=No\"";
System.Data.OleDb.OleDbConnection TextConnection = new System.Data.OleDb.OleDbConnection(ConnectionString);
OleDbCommand TextCommand = new OleDbCommand("SELECT * FROM OrdersTest#csv", TextConnection);
TextConnection.Open();
OleDbDataReader TextDataReader = TextCommand.ExecuteReader(CommandBehavior.SequentialAccess);
// Open the destination connection.
using (SqlConnection DestinationConnection = new SqlConnection(SQLConnectionString)) {
DestinationConnection.Open();
// Set up the bulk copy object.
// The column positions in the source data reader
// match the column positions in the destination table,
// so there is no need to map columns.
using (SqlBulkCopy BulkCopy = new SqlBulkCopy(DestinationConnection)) {
BulkCopy.DestinationTableName = "dbo.Orders";
try {
// Write from the source to the destination.
BulkCopy.WriteToServer(TextDataReader);
} catch (Exception ex) {
Console.WriteLine(ex.Message);
} finally {
// Close the AccessDataReader. The SqlBulkCopy
// object is automatically closed at the end
// of the Using block.
TextDataReader.Close();
}
}
// Perform a final count on the destination table
// to see how many rows were added.
long CountEnd = System.Convert.ToInt32(CommandRowCount.ExecuteScalar());
//Console.WriteLine("Ending row count = {0}", CountEnd)
//Console.WriteLine("{0} rows were added.", CountEnd - CountStart)
}
}
//Dim FILE_NAME As String = "C:\Users\Excel\Desktop\OrdersTest.csv"
//Dim TextLine As String
//If System.IO.File.Exists(FILE_NAME) = True Then
// Dim objReader As New System.IO.StreamReader(FILE_NAME)
// Do While objReader.Peek() <> -1
// TextLine = TextLine & objReader.ReadLine() & vbNewLine
// Loop
//Else
// MsgBox("File Does Not Exist")
//End If
//Dim cn As New SqlConnection("Data Source=Excel-PC\SQLEXPRESS;Initial Catalog=Northwind;Trusted_Connection=True;")
//Dim cmd As New SqlCommand
//cmd.Connection = cn
//cmd.Connection.Close()
//cmd.Connection.Open()
//cmd.CommandText = "INSERT INTO Orders (OrderID,CustomerID,EmployeeID,OrderDate,RequiredDate,ShippedDate,ShipVia,Freight,ShipName,ShipAddress,ShipCity,ShipRegion,ShipPostalCode,ShipCountry) values & OrdersTest.csv"
//cmd.ExecuteNonQuery()
//cmd.Connection.Close()
}
private void Button6_Click(System.Object sender, System.EventArgs e)
{
// Define the Column Definition
DataTable dt = new DataTable();
dt.Columns.Add("OrderID", typeof(int));
dt.Columns.Add("CustomerID", typeof(string));
dt.Columns.Add("EmployeeID", typeof(int));
dt.Columns.Add("OrderDate", typeof(System.DateTime));
dt.Columns.Add("RequiredDate", typeof(System.DateTime));
dt.Columns.Add("ShippedDate", typeof(System.DateTime));
dt.Columns.Add("ShipVia", typeof(int));
dt.Columns.Add("Freight", typeof(decimal));
dt.Columns.Add("ShipName", typeof(string));
dt.Columns.Add("ShipAddress", typeof(string));
dt.Columns.Add("ShipCity", typeof(string));
dt.Columns.Add("ShipRegion", typeof(string));
dt.Columns.Add("ShipPostalCode", typeof(string));
dt.Columns.Add("ShipCountry", typeof(string));
using (cn == new SqlConnection("Server='Server_Name';Database='Database_Name';Trusted_Connection=True;")) {
cn.Open();
Microsoft.VisualBasic.FileIO.TextFieldParser reader = default(Microsoft.VisualBasic.FileIO.TextFieldParser);
string[] currentRow = null;
DataRow dr = default(DataRow);
string sqlColumnDataType = null;
reader = My.Computer.FileSystem.OpenTextFieldParser("C:\\Users\\Excel\\Desktop\\OrdersTest.csv");
reader.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited;
reader.Delimiters = new string[] { "," };
while (!reader.EndOfData) {
try {
currentRow = reader.ReadFields();
dr = dt.NewRow();
for (currColumn = 0; currColumn <= dt.Columns.Count - 1; currColumn++) {
sqlColumnDataType = dt.Columns(currColumn).DataType.Name;
switch (sqlColumnDataType) {
case "String":
if (string.IsNullOrEmpty(currentRow(currColumn))) {
dr.Item(currColumn) = "";
} else {
dr.Item(currColumn) = Convert.ToString(currentRow(currColumn));
}
break;
case "Decimal":
if (string.IsNullOrEmpty(currentRow(currColumn))) {
dr.Item(currColumn) = 0;
} else {
dr.Item(currColumn) = Convert.ToDecimal(currentRow(currColumn));
}
break;
case "DateTime":
if (string.IsNullOrEmpty(currentRow(currColumn))) {
dr.Item(currColumn) = "";
} else {
dr.Item(currColumn) = Convert.ToDateTime(currentRow(currColumn));
}
break;
}
}
dt.Rows.Add(dr);
} catch (Microsoft.VisualBasic.FileIO.MalformedLineException ex) {
Interaction.MsgBox("Line " + ex.Message + "is not valid." + Constants.vbCrLf + "Terminating Read Operation.");
reader.Close();
reader.Dispose();
//Return False
} finally {
dr = null;
}
}
using (SqlBulkCopy copy = new SqlBulkCopy(cn)) {
copy.DestinationTableName = "[dbo].[Orders]";
copy.WriteToServer(dt);
}
}
}
public static bool GetCsvData(string CSVFileName, ref DataTable CSVTable)
{
Microsoft.VisualBasic.FileIO.TextFieldParser reader = default(Microsoft.VisualBasic.FileIO.TextFieldParser);
string[] currentRow = null;
DataRow dr = default(DataRow);
string sqlColumnDataType = null;
reader = My.Computer.FileSystem.OpenTextFieldParser(CSVFileName);
reader.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited;
reader.Delimiters = new string[] { "," };
while (!reader.EndOfData) {
try {
currentRow = reader.ReadFields();
dr = CSVTable.NewRow();
for (currColumn = 0; currColumn <= CSVTable.Columns.Count - 1; currColumn++) {
sqlColumnDataType = CSVTable.Columns(currColumn).DataType.Name;
switch (sqlColumnDataType) {
case "String":
if (string.IsNullOrEmpty(currentRow(currColumn))) {
dr.Item(currColumn) = "";
} else {
dr.Item(currColumn) = Convert.ToString(currentRow(currColumn));
}
break;
case "Decimal":
if (string.IsNullOrEmpty(currentRow(currColumn))) {
dr.Item(currColumn) = 0;
} else {
dr.Item(currColumn) = Convert.ToDecimal(currentRow(currColumn));
}
break;
case "DateTime":
if (string.IsNullOrEmpty(currentRow(currColumn))) {
dr.Item(currColumn) = "";
} else {
dr.Item(currColumn) = Convert.ToDateTime(currentRow(currColumn));
}
break;
}
}
CSVTable.Rows.Add(dr);
} catch (Microsoft.VisualBasic.FileIO.MalformedLineException ex) {
Interaction.MsgBox("Line " + ex.Message + "is not valid." + Constants.vbCrLf + "Terminating Read Operation.");
reader.Close();
reader.Dispose();
return false;
} finally {
dr = null;
}
}
reader.Close();
reader.Dispose();
return true;
}
}
//=======================================================
//Service provided by Telerik (www.telerik.com)
//Conversion powered by NRefactory.
//Twitter: #telerik
//Facebook: facebook.com/telerik
//=======================================================

C# Iterate through rows in a DataTable

I'm trying to Iterate through rows in a 2 column table to check 1 field in each row against a Name. Once found I want to code to assign the corresponding Number to the OurNumber variable, and break out of the loop by setting GotTheNumber to true.
Below is the code I'm using:
private void BtnDelete_Click(object sender, EventArgs e)// Sends to ConfirmDeleteEMP Form
{
ConfirmDeleteEMP form = new ConfirmDeleteEMP();
DataTable table = new DataTable();
string connstring = #"Provider = Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\\HoliPlanData.accdb;Persist Security Info=False";
using (OleDbConnection conn = new OleDbConnection(connstring))
{
string query = "SELECT PayrollNo, (FirstName + ' ' + LastName) AS NAME FROM [Employee]";
OleDbDataAdapter adapter = new OleDbDataAdapter(query, conn);
adapter.Fill(table);
}
string SelectedName = DropBoxEmp.Text;
bool GotTheNumber = false;
int OurNumber = 0;
while (!GotTheNumber)
{
foreach (DataRow ThisRow in table.Rows)
{
if (SelectedName = (table.Rows[ThisRow]))
{
OurNumber = ///THATNUMBER///;
GotTheNumber = true;
}
}
}
MessageBox.Show(SelectedName);
var GoodNumber = (table.Rows[OurNumber]["PayrollNo"].ToString());
form.PassValueName = SelectedName;
form.PassSelectedPayroll = GoodNumber;
form.Tag = this;
form.Show(this);
Hide();
}
I don't know where to go from the If statement, so any help would be greatly appreciated.

Looping through the rows in your client program is exactly what you don't want to do. Let the database do that work for you. Try this:
private void BtnDelete_Click(object sender, EventArgs e)// Sends to ConfirmDeleteEMP Form
{
object result;
string query = "SELECT PayrollNo FROM [Employee] WHERE FirstName + ' ' + LastName = ?";
string connstring = #"Provider = Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\\HoliPlanData.accdb;Persist Security Info=False";
using (OleDbConnection conn = new OleDbConnection(connstring))
using (OleDbCommand cmd = new OleDbCommand(query, conn))
{
//guessing at type and length here
cmd.Parameters.Add("?", OleDbType.VarWChar, 50).Value = DropBoxEmp.Text;
conn.Open();
result = cmd.ExecuteScalar();
}
if (result != null && result != DBNull.Value)
{
ConfirmDeleteEMP form = new ConfirmDeleteEMP();
form.PassValueName = DropBoxEmp.Text;
form.PassSelectedPayroll = (int)result;
form.Tag = this;
form.Show(this);
Hide();
}
}
If you really want to loop through the rows against all reason (it's slower, requires writing more code, and it's more error-prone), you can do this:
private void BtnDelete_Click(object sender, EventArgs e)// Sends to ConfirmDeleteEMP Form
{
DataTable table = new DataTable();
string query = "SELECT PayrollNo, (FirstName + ' ' + LastName) AS NAME FROM [Employee]";
string connstring = #"Provider = Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\\HoliPlanData.accdb;Persist Security Info=False";
using (OleDbConnection conn = new OleDbConnection(connstring))
{
OleDbDataAdapter adapter = new OleDbDataAdapter(query, conn);
adapter.Fill(table);
}
int PayrollNumber = 0;
foreach (DataRow ThisRow in table.Rows)
{
if (DropBoxEmp.Text == ThisRow["NAME"])
{
PayrollNumber = (int)ThisRow["PayrollNo"];
break;
}
}
//the whole loop could also be consolidated to this:
//PayrollNumber = (int)table.Rows.First(r => r["NAME"] == DropBoxEmp.Text)["PayrollNo"];
ConfirmDeleteEMP form = new ConfirmDeleteEMP();
form.PassValueName = DropBoxEmp.Text;
form.PassSelectedPayroll = PayrollNumber ;
form.Tag = this;
form.Show(this);
Hide();
}

Hm, hard to guess what exactly your problem is. But I think you just want to get the PayrollNo from the current row, aren't you?
Regarding the line further down ...
var GoodNumber = (table.Rows[OurNumber]["PayrollNo"].ToString());
... I think you could just call:
if (...)
{
OurNumber = ThisRow["PayrollNo"].ToString();
GotTheNumber = true;
}
However, I have no clue what you are doing with the following if-condition and if this really does what you want it to do:
if (SelectedName = (table.Rows[ThisRow]))
{
...
}

get all row and column data using SELECT - C#

I'm trying to get all data from an SQL table and store it in a List using the C# programming language.
the SQL statement I'm using is:
private string cmdShowEmployees = "SELECT * FROM Employees;";
This is being used in the same class as a function
public List<string> showAllIdData()
{
List<string> id = new List<string>();
using (sqlConnection = getSqlConnection())
{
sqlCommand.Connection = sqlConnection;
sqlCommand.CommandText = cmdShowEmployees;
SqlDataReader reader = sqlCommand.ExecuteReader();
while (reader.Read()) {
id.Add(reader[0].ToString());
}
return id;
}
}
and here
public List<string> showAllActiveData()
{
List<string> active = new List<string>();
using (sqlConnection = getSqlConnection())
{
sqlCommand.Connection = sqlConnection;
sqlCommand.CommandText = cmdShowEmployees;
SqlDataReader reader = sqlCommand.ExecuteReader();
while (reader.Read()) {
active.Add(reader[1].ToString());
}
return active;
}
I would have to create 9 more functions this way in order to get all the data out of the Employees table. This seems very inefficient and I was wondering if there was a more elegant way to do this.
I know using an adapter is one way to do it but I don't think it is possible to convert a filled adapter to a list, list list etc.
SqlDataAdapter adapter = sqlDataCollection.getAdapter();
DataSet dataset = new DataSet();
adapter.Fill(dataset, "idEmployees");
dataGridView1.DataSource = dataset;
dataGridView1.DataMember = "idEmployees";
Any ideas?

If you must use the reader in this way, why not create an object which holds the table row data.
public class SomeComplexItem
{
public string SomeColumnValue { get; set;}
public string SomeColumnValue2 { get; set;}
public string SomeColumnValue3 { get; set;}
public string SomeColumnValue4 { get; set;}
}
That way you can loop through with your reader as follows:
public List<SomeComplexItem> showAllActiveData()
{
List<SomeComplexItem> active = new List<SomeComplexItem>();
using (sqlConnection = getSqlConnection())
{
sqlCommand.Connection = sqlConnection;
sqlCommand.CommandText = cmdShowEmployees;
SqlDataReader reader = sqlCommand.ExecuteReader();
while (reader.Read())
{
var someComplexItem = new SomeComplexItem();
someComplexItem.SomeColumnValue = reader[1].ToString();
someComplexItem.SomeColumnValue2 = reader[2].ToString();
someComplexItem.SomeColumnValue3 = reader[3].ToString();
active.Add(someComplexItem);
}
return active;
}

You could use two select statements to populate two List<string> as shown in the example below where the key between reads is reader.NextResult();.
The database used is the standard Microsoft NorthWind database.
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
namespace SQL_Server_TwoList
{
public class DataOperations
{
public List<string> Titles { get; set; }
public List<string> Names { get; set; }
/// <summary>
/// Trigger code to load two list above
/// </summary>
public DataOperations()
{
Titles = new List<string>();
Names = new List<string>();
}
public bool LoadData()
{
try
{
using (SqlConnection cn = new SqlConnection(Properties.Settings.Default.ConnectionString))
{
string commandText = #"
SELECT [TitleOfCourtesy] + ' ' + [LastName] + ' ' + [FirstName] As FullName FROM [NORTHWND.MDF].[dbo].[Employees];
SELECT DISTINCT [Title] FROM [NORTHWND.MDF].[dbo].[Employees];";
using (SqlCommand cmd = new SqlCommand(commandText, cn))
{
cn.Open();
SqlDataReader reader = cmd.ExecuteReader();
// get results into first list from first select
if (reader.HasRows)
{
while (reader.Read())
{
Names.Add(reader.GetString(0));
}
// move on to second select
reader.NextResult();
// get results into first list from first select
if (reader.HasRows)
{
while (reader.Read())
{
Titles.Add(reader.GetString(0));
}
}
}
}
}
return true;
}
catch (Exception)
{
return false;
}
}
}
}
Form code
namespace SQL_Server_TwoList
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
DataOperations dataOps = new DataOperations();
if (dataOps.LoadData())
{
listBox1.DataSource = dataOps.Names;
listBox2.DataSource = dataOps.Titles;
}
}
}
}

You could always add it all to a dataset or datatable instead of looping through using datareader to add to an array, dataset allows you to access data in similar way to array anyway.
Connstr = "Data Source = " + SelectedIP + "; Initial Catalog = " + dbName + "; User ID = " + txtUsername.Text +"; Password = "+ txtPassword.Text +"";
conn = new SqlConnection(Connstr);
try
{
string contents = "SELECT * FROM ..."
conn.Open();
SqlDataAdapter da_1 = new SqlDataAdapter(contents, conn); //create command using contents of sql file
da_1.SelectCommand.CommandTimeout = 120; //set timeout in seconds
DataSet ds_1 = new DataSet(); //create dataset to hold any errors that are rturned from the database
try
{
//manipulate database
da_1.Fill(ds_1);
if (ds_1.Tables[0].Rows.Count > 0) //loop through all rows of dataset
{
for (int i = 0; i < ds_1.Tables[0].Rows.Count; i++)
{
//rows[rownumber][column number/ "columnName"]
Console.Write(ds_1.Tables[0].Rows[i][0].ToString() + " ");
}
}
}
catch(Exception err)
{}
conn.Close();
}
catch(Exception ex)
{}

How to retrieve the value of first index through ComboBox in C#.Net?

I kept getting "FormatException was unhandled by user Code"
Following is the Code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Configuration;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace Eventmanagement
{
public partial class Registration : Form
{
SqlConnection aConnection;
string firstname= string.Empty;
string lastname= string.Empty;
int aid;
string date = DateTime.Now.ToShortDateString();
SqlDataAdapter da = new SqlDataAdapter();
DataTable dta;
public Registration(string fname, string lname, int attID)
{
this.firstname = fname;
this.lastname = lname;
this.aid = attID;
InitializeComponent();
}
//--------------------------------------------//
private void Registration_Load(object sender, EventArgs e)
{
// TODO: This line of code loads data into the 'insertEventDataSet.Events' table. You can move, or remove it, as needed.
populateEventSalesPersonList();
populateEventNameIdTypeList();
//+++++++++++++++++++++++++++++++++++++++++++//
txtSalesTaxRate_Registration.Text = Convert.ToString( SalesTaxRate());
txtRegistrationID_Registration.Text = regID().ToString();
//+++++++++++++++++++++++++++++++++++++++++++//
//+++++++++++++++++++++++++++++++++++++++++++//
txtAttendee_Registration.Text = (this.firstname+" "+this.lastname);
txtRegistrationDate_Registration.Text = date.ToString();
}
//--------------------------------------------//
public string getConnectionString()
{
try
{
string sConnection = "";
// Get the mapped configuration file.
System.Configuration.ConnectionStringSettingsCollection ConnSettings = ConfigurationManager.ConnectionStrings;
sConnection = ConnSettings["DBConnectionString"].ToString();
return sConnection;
}
catch (Exception err)
{
MessageBox.Show(err.Message);
return "";
}
}
//--------------------------------------------//
public void populateEventNameIdTypeList()
{
try
{
cmbEvent_Registration.DataSource = getDataTable4();
//----------------------------
cmbEvent_Registration.ValueMember = "EventID";
cmbEvent_Registration.DisplayMember = "EventName";
}
catch (Exception err)
{
MessageBox.Show(err.Message);
}
}
//--------------------------------------------//
public void populateEventSalesPersonList()
{
try
{
cmbSalesPerson_Registration.DataSource = getDataTable5();
cmbSalesPerson_Registration.ValueMember = "EmployeeID";
cmbSalesPerson_Registration.DisplayMember = "SalesPerson";
}
catch (Exception err)
{
MessageBox.Show(err.Message);
}
}
//-------------------------------------------//
public void populateFeeScheduleByEventList()
{
try
{
cmbFeeSchedule_Registration.DataSource = getDataTable6();
cmbFeeSchedule_Registration.ValueMember = "FeeScheduleID";
cmbFeeSchedule_Registration.DisplayMember = "Fee";
//--------------------------------------------------//
//saleTax();
//txtSalesTax_Registration.Text = Convert.ToString(saleTax());
//txtTotalCharges_Registration.Text = Convert.ToString(totalCharges());
//txtAmountDue_Registration.Text = Convert.ToString(amountDue());
//--------------------------------------------------//
}
catch (Exception err)
{
MessageBox.Show(err.Message);
}
}
//------------------------------------------//
//------------------------------------------//
private void btnclose_Registration_Click(object sender, EventArgs e)
{
this.Close();
}
private void btnInsert_Registration_Click(object sender, EventArgs e)
{
try
{
aConnection = new SqlConnection(getConnectionString());
aConnection.Open();
//Calling the Stored Procedure
da.InsertCommand = new SqlCommand("RegistrationInsert", aConnection);
da.InsertCommand.CommandType = CommandType.StoredProcedure;
//da.InsertCommand.Parameters.Add(#"RegistrationID", SqlDbType.Int).Value = Convert.ToInt16( txtRegistrationID_Registration.Text);
da.InsertCommand.Parameters.Add(#"AttendeeID", SqlDbType.Int).Value = Convert.ToInt16( aid);
da.InsertCommand.Parameters.Add(#"RegistrationDate", SqlDbType.SmallDateTime).Value = Convert.ToDateTime(txtRegistrationDate_Registration.Text=date.ToString());
da.InsertCommand.Parameters.Add(#"PurchaseOrderNumber", SqlDbType.VarChar).Value = txtPoNumber_Registration.Text;
// da.InsertCommand.Parameters.Add(#"SalesPerson", SqlDbType.Int).Value = Convert.ToInt64(cmbSalesPerson_Registration.SelectedValue.ToString());
da.InsertCommand.Parameters.Add(#"EventID", SqlDbType.Int).Value = cmbEvent_Registration.SelectedValue.ToString();
da.InsertCommand.Parameters.Add(#"FeeScheduleID", SqlDbType.Int).Value = cmbFeeSchedule_Registration.SelectedValue.ToString();
da.InsertCommand.Parameters.Add(#"RegistrationFee", SqlDbType.Money).Value = txtRegistrationFee_Registration.Text;
da.InsertCommand.Parameters.Add(#"EmployeeID", SqlDbType.Int).Value = Convert.ToInt16(cmbSalesPerson_Registration.SelectedValue.ToString());
da.InsertCommand.Parameters.Add(#"SalesTaxRate", SqlDbType.Float).Value = txtSalesTaxRate_Registration.Text;
//da.InsertCommand.Parameters.Add(#"EndTime", SqlDbType.SmallDateTime).Value = Convert.ToDateTime(txtEndTime.Text.ToString());
da.InsertCommand.ExecuteNonQuery();
MessageBox.Show("Inserted successfully!!!");
aConnection.Close();
da.InsertCommand.Dispose();
}
catch (Exception err)
{
MessageBox.Show(err.Message);
}
}
//-------------------------------------------//
public DataTable getDataTable4()
{
try
{
dta = new DataTable();
aConnection = new SqlConnection(getConnectionString());
aConnection.Open();
da = new SqlDataAdapter();
da.SelectCommand = new SqlCommand("EventsSelectAll", aConnection);
da.SelectCommand.CommandType = CommandType.StoredProcedure;
da.SelectCommand.ExecuteNonQuery();
da.Fill(dta);
aConnection.Close();
return dta;
}
catch (Exception err)
{
MessageBox.Show(err.Message);
return null;
}
}
public DataTable getDataTable5()
{
try
{
dta = new DataTable();
aConnection = new SqlConnection(getConnectionString());
aConnection.Open();
da = new SqlDataAdapter();
da.SelectCommand = new SqlCommand("sp_RegistrationSalesPerson", aConnection);
da.SelectCommand.CommandType = CommandType.StoredProcedure;
da.SelectCommand.ExecuteNonQuery();
dta.Clear();
da.Fill(dta);
aConnection.Close();
return dta;
}
catch (Exception err)
{
MessageBox.Show(err.Message);
return null;
}
}
public DataTable getDataTable6()
{
try
{
dta = new DataTable();
da = new SqlDataAdapter();
aConnection = new SqlConnection(getConnectionString());
aConnection.Open();
da.SelectCommand = new SqlCommand("sp_FeeScheduleSelectAllByEventID", aConnection);
da.SelectCommand.Parameters.Add("EventID", SqlDbType.Int).Value = Convert.ToInt32(cmbEvent_Registration.SelectedValue.ToString());
da.SelectCommand.CommandType = CommandType.StoredProcedure;
da.SelectCommand.ExecuteNonQuery();
da.Fill(dta);
aConnection.Close();
return dta;
}
catch (Exception err)
{
MessageBox.Show(err.Message);
return null;
}
}
private void cmbEvent_Registration_SelectedIndexChanged(object sender, EventArgs e)
{
populateFeeScheduleByEventList();
txtRemainingSeats_Registration.Text = Convert.ToString(spaces());
}
public double saleTax()
{
double regFee = Convert.ToDouble(cmbFeeSchedule_Registration.SelectedText);
double sTR = Convert.ToDouble(SalesTaxRate());
double sr = regFee * (sTR / 100);
return sr;
}
public int totalRegisteredAttendees()
{
da = new SqlDataAdapter();
aConnection = new SqlConnection(getConnectionString());
da.SelectCommand = new SqlCommand("RegistrationSelectAllByEventID", aConnection);
da.SelectCommand.CommandType = CommandType.StoredProcedure;
da.SelectCommand.Parameters.Add("EventID", SqlDbType.Int).Value = Convert.ToInt32(cmbEvent_Registration.SelectedValue.ToString());
aConnection.Open();
int val = (int)da.SelectCommand.ExecuteScalar();
aConnection.Close();
return val;
}
public int spaces()
{
da = new SqlDataAdapter();
aConnection = new SqlConnection(getConnectionString());
da.SelectCommand = new SqlCommand("EventsSelect", aConnection);
da.SelectCommand.CommandType = CommandType.StoredProcedure;
da.SelectCommand.Parameters.Add("EventID", SqlDbType.Int).Value = Convert.ToInt32(cmbEvent_Registration.SelectedValue.ToString());
aConnection.Open();
int spaces = Convert.ToInt16(da.SelectCommand.ExecuteScalar());
aConnection.Close();
int value = totalRegisteredAttendees();
int totalspaces = spaces - value;
return totalspaces;
}
public double SalesTaxRate()
{
da = new SqlDataAdapter();
aConnection = new SqlConnection(getConnectionString());
da.SelectCommand = new SqlCommand("CompanyInfo", aConnection);
da.SelectCommand.CommandType = CommandType.StoredProcedure;
aConnection.Open();
double sale = Convert.ToDouble(da.SelectCommand.ExecuteScalar());
aConnection.Close();
return sale;
}
public double totalCharges()
{
double tc = Convert.ToDouble(txtRegistrationFee_Registration.Text) + (saleTax());
return tc;
}
public double amountDue()
{
double aD;
if (txtTotalPaid_Registration.Text == string.Empty)
{
aD = Convert.ToDouble(txtTotalCharges_Registration.Text.ToString());
}
else
{
double a = Convert.ToDouble(txtTotalPaid_Registration.Text.ToString());
double b= (Convert.ToDouble(txtTotalCharges_Registration.Text.ToString()));
aD = b-a;
}
return aD;
}
public int regID()
{
da = new SqlDataAdapter();
aConnection = new SqlConnection(getConnectionString());
da.SelectCommand = new SqlCommand("RegistrationID", aConnection);
da.SelectCommand.CommandType = CommandType.StoredProcedure;
aConnection.Open();
int id = ((int)da.SelectCommand.ExecuteScalar())+1;
aConnection.Close();
return id;
}
private void cmbFeeSchedule_Registration_SelectedIndexChanged(object sender, EventArgs e)
{
saleTax();
}
//------------------------------------------//
}
}
When I call SaleTax() Method in following
private void cmbFeeSchedule_Registration_SelectedIndexChanged(object sender, EventArgs e)
{
saleTax();
}
I get "FormatException was unhandled by user Code" Error
I debugged the Code and find out that it is happening because cmbFeeSchedule_Registration is not selecting the first index, hence it is giving the error. I am confused what to do?
How I get around this Problem?
Edit:
Well I resolved the issue. It was the problem of in ` public void populateFeeScheduleByEventList()
{
try
{
cmbFeeSchedule_Registration.DataSource = getDataTable6();
cmbFeeSchedule_Registration.ValueMember = "FeeScheduleID";
cmbFeeSchedule_Registration.DisplayMember = "Fee";
catch (Exception err)
{
MessageBox.Show(err.Message);
}
}`
When SaleTax() was called, pointer leaves the DisplayMember and ValueMember. Hence I readjusted the code little bit and placed cmbFeeSchedule_Registration.ValueMember = "FeeScheduleID"; cmbFeeSchedule_Registration.DisplayMember = "Fee"; before
cmbFeeSchedule_Registration.DataSource = getDataTable6(); and it resolved the Problem. :)

If it is required that index 0 be selected in your ComboBox then you need to do some basic checking. In your SelectedIndexChanged EventHandler wire-up, you need to add:
if (cmbFeeSchedule_Registration.SelectedIndex == 0) {
salesTax();
}
Also if the user is able to change the text in the ComboBox, you are not doing any error handling to handle the FormatException that will be caused by Convert.ToDouble when trying to convert a non-double value that is not parsable.
double regFee = Convert.ToDouble(cmbFeeSchedule_Registration.SelectedText);
double sTR = Convert.ToDouble(SalesTaxRate());
Furthermore, you could actually use double.Parse or double.TryParse instead of ConvertTo, which seems more proper. On another note, if the user cannot edit the text in the ComboBox (say you have it set to DropDownList), you should use the SelectedObject or SelectedValue property instead of SelectedText depending if it is DataBound or not.
Bottom line is you need to make sure you are checking that the correct index is selected before calling salesTax() or any operation that will potentially throw an exception, and do error checking to ensure that your values are what they should be. If regFee is anything but a double, because the correct index is not selected, ConvertTo will fail. (Use double.Parse/TryParse instead, anyway)
A tip of advice when posting questions is to only post the affected segment of code, and provide a StackTrace when one is available. It's too difficult to navigate all of your code on here, and using a StackTrace it is easy to break down.

you have to make selectedindex = 0 in your form

Just do this:
if(((ComboBox)sender).SelectedIndex > -1) saleTax();
instead. If you want to select the first item when the form loads, set SelectedIndex in the Load event.

Develop Reference

C# (C-Sharp) is a programming language developed by Microsoft that runs on the .NET Framework.

The connection is open - c#

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();

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get all row and column data using SELECT - C#

How to retrieve the value of first index through ComboBox in C#.Net?

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