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Unable to cast object of type 'System.DBNull' to type 'System.DateTime'

Hi im trying to make a notification system. Basically when i add a new row, a notification will be shown on my notificationspage realtime (i use signalR with razor pages asp.net). But for some reason when i get on that page, i get these errors: Unable to cast object of type 'System.DBNull' to type 'System.DateTime'.
at myWebApp.Controllers.SpeedListener.GetAlarmList() in \myWebApp\Controllers\SpeedListener.cs:line 83
at myWebApp.Controllers.SpeedListener.ListenForAlarmNotifications() in \myWebApp\Controllers\SpeedListener.cs:line 43
So apparently theres a problem at the controller.
Here is the code of the controller
namespace myWebApp.Controllers
{
public class SpeedListener :Controller
{
private IHubContext<speedalarmhub> _hubContext;
private IMemoryCache _cache;
public SpeedListener(IHubContext<speedalarmhub> hubContext,IMemoryCache cache)
{
_hubContext = hubContext;
_cache = cache;
}
public static string cs = Database.Database.Connector();
public void ListenForAlarmNotifications()
{
NpgsqlConnection conn = new NpgsqlConnection(cs);
conn.StateChange += conn_StateChange;
conn.Open();
var listenCommand = conn.CreateCommand();
listenCommand.CommandText = $"listen notifytickets;";
listenCommand.ExecuteNonQuery();
conn.Notification += PostgresNotificationReceived;
_hubContext.Clients.All.SendAsync(this.GetAlarmList());
while (true)
{
conn.Wait();
}
}
private void PostgresNotificationReceived(object sender, NpgsqlNotificationEventArgs e)
{
string actionName = e.Payload.ToString();
string actionType = "";
if (actionName.Contains("DELETE"))
{
actionType = "Delete";
}
if (actionName.Contains("UPDATE"))
{
actionType = "Update";
}
if (actionName.Contains("INSERT"))
{
actionType = "Insert";
}
_hubContext.Clients.All.SendAsync("ReceiveMessage", this.GetAlarmList());
}
public string GetAlarmList()
{
List<NotificationModel> not = new List<NotificationModel>();
using var con = new NpgsqlConnection(cs);
{
string query = "Select datumnu, bericht FROM notification";
using NpgsqlCommand cmd = new NpgsqlCommand(query, con);
{
cmd.Connection = con;
con.Open();
using (NpgsqlDataReader dr = cmd.ExecuteReader())
{
while (dr.Read())
{
not.Add(new NotificationModel { Datenow = ((DateTime) dr["datumnu"]).ToString("yyyy/MM/dd"), Bericht = dr["bericht"].ToString() });
}
}
con.Close();
}
}
_cache.Set("notification", SerializeObjectToJson(not));
return _cache.Get("notification").ToString();
}
public String SerializeObjectToJson(Object notification)
{
try
{
return Newtonsoft.Json.JsonConvert.SerializeObject(notification);
}
catch (Exception) { return null; }
}
private void conn_StateChange(object sender, System.Data.StateChangeEventArgs e)
{
_hubContext.Clients.All.SendAsync("Current State: " + e.CurrentState.ToString() + " Original State: " + e.OriginalState.ToString(), "connection state changed");
}
}
}
If needed here is my hub
namespace myWebApp.Hubs
{
public class speedalarmhub : Hub
{
private IMemoryCache _cache;
private IHubContext<speedalarmhub> _hubContext;
public speedalarmhub(IMemoryCache cache, IHubContext<speedalarmhub> hubContext)
{
_cache = cache;
_hubContext = hubContext;
}
public async Task SendMessage()
{
if (!_cache.TryGetValue("notification", out string response))
{
SpeedListener speedlist = new SpeedListener(_hubContext,_cache);
speedlist.ListenForAlarmNotifications();
string jsonspeedalarm = speedlist.GetAlarmList();
_cache.Set("notification", jsonspeedalarm);
await Clients.All.SendAsync("ReceiveMessage", _cache.Get("notification").ToString());
}
else
{
await Clients.All.SendAsync("ReceiveMessage", _cache.Get("notification").ToString());
}
}
}
}
the table name in postgresql is called 'notification', i have two column called 'bericht' with type varchar and 'datumnu' with type date.

Edit suggested by mjwills
DateTime don't accept null value. Check if the value is null and assigne a default value
while (dr.Read())
{
not.Add(new NotificationModel { Datenow = ((DateTime) dr["datumnu"]).ToString("yyyy/MM/dd"), Bericht = dr["bericht"].ToString() });
}
Become
while (dr.Read())
{
DateTime defaultDateTime = DateTime.Now;
if(dr.IsNull("datumnu")){
defaultDateTime = (DateTime)dr["datumnu"];
}
not.Add(new NotificationModel { Datenow = defaultDateTime, Bericht = dr["bericht"].ToString() });
}
in single line
while (dr.Read())
{
not.Add(new NotificationModel { Datenow = (dr.IsNull("datumnu") ? DateTime.Now : (DateTime)dr["datumnu"]), Bericht = dr["bericht"].ToString() });
}

How to add data into MSQL database by using c# programming?

Good day!
Using visual studio 2012, I have created a Student class with get and set codes, and i need to complete the StudentDAO class to create insert coding that will use to store data to database student table. this action is perform by a windows form button click event.
what i need to create a button click code and then insert into database code,
//Student.cs class
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace SRSJason
{
class Student
{
private string S_Student_id;
private string S_Full_name;
private DateTime S_Dob;
private string S_Address;
private int S_Contact;
private string S_Username;
private string S_Password;
public Student() //Default constructor
{
}
public Student(string Student_id, string Full_name, DateTime Dob, string Address, int Contact, string Username, string Password) //Overloadign
{
S_Student_id = Student_id;
S_Full_name = Full_name;
S_Dob = Dob;
S_Address = Address;
S_Contact = Contact;
S_Username = Username;
S_Password = Password;
}
public void setID(string Student_id)
{
S_Student_id = Student_id;
}
public string getID()
{
return S_Student_id;
}
public void setName(string Full_name)
{
S_Full_name = Full_name;
}
public string getName()
{
return S_Full_name;
}
public void setDob(DateTime Dob)
{
S_Dob = Dob;
}
public DateTime getDob()
{
return S_Dob;
}
public void setAddress(string Address)
{
S_Address = Address;
}
public string getAddress()
{
return S_Address;
}
public void setContact(int Contact)
{
S_Contact = Contact;
}
public int getContact()
{
return S_Contact;
}
public void setUsername(string Username)
{
S_Username = Username;
}
public string getUsername()
{
return S_Username;
}
public void setPassword(string Password)
{
S_Password = Password;
}
public string getPassword()
{
return S_Password;
}
}
}`
//StudentDAO class (please help me to complete this code)
`class StudentDAO
{
static string constring = "Data Source=JAZE;Initial Catalog=srsjason;Integrated Security=True";
SqlConnection m_con = new SqlConnection(constring);
}`
//button click from the form (please help me to complete this code as well)
private void submitstudent(object sender, EventArgs e)
{
}
please help me to complete this coding

First of all when you create private properties u cant access them in your forms, you have to create a method instead inside the same class then use it in your form. second you should know about the ORM - Object Relational Mapping that you are using.
Here I'll list them:
ADO.NET
LINQ to SQL
ADO.NET Entity Framework
When you picked one of those. next step would be learning about how they work and whats the syntax.
However knowing that you kinda showed a syntax of ADO.NET Here is an Example how you can insert the data in your data base using ADO.NET. If you want to add data directly from code-behind without a method. so basically on click event of your button.
private void btn_Click(object sender, EventArgs e)
{
try
{
//create object of Connection Class..................
SqlConnection con = new SqlConnection();
// Set Connection String property of Connection object..................
con.ConnectionString = "Data Source=KUSH-PC;Initial Catalog=test;Integrated Security=True";
// Open Connection..................
con.Open();
//Create object of Command Class................
SqlCommand cmd = new SqlCommand();
//set Connection Property of Command object.............
cmd.Connection = con;
//Set Command type of command object
//1.StoredProcedure
//2.TableDirect
//3.Text (By Default)
cmd.CommandType = CommandType.Text;
//Set Command text Property of command object.........
cmd.CommandText = "Insert into Registration (Username, password) values ('#user','#pass')";
//Assign values as `parameter`. It avoids `SQL Injection`
cmd.Parameters.AddWithValue("user", TextBox1.text);
cmd.Parameters.AddWithValue("pass", TextBox2.text);
//Execute command by calling following method................
//1.ExecuteNonQuery()
//This is used for insert,delete,update command...........
//2.ExecuteScalar()
//This returns a single value .........(used only for select command)
//3.ExecuteReader()
//Return one or more than one record.
cmd.ExecuteNonQuery();
con.Close();
MessageBox.Show("Data Saved");
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
con.Close();
}
}
Be sure that you've included your ConnectionString in your config file.

Update Collection Value with Database in UWP(MVVM)

I have custom collection which contains student_id,student_name,student_mark.And having the table with same columns in the database as well. The design form have some controls for updating the existing student.
Temporarily all the updating operations are done with that custom collection.Lets assume we have 100 students data in collection and database. Any updating operation should reflect in the collection. But what my doubt is how do i update these values with the database before i close the application??
But when i open the application the collection should have all the values which have stored in the database.

But what my doubt is how do i update these values with the database
Firstly, you need to know how to do CRUD operations on MySQL database with uwp app. For this, please reference this sample.
Secondly, according to your description, you have built up a MVVM project to bind a collection data to the view. But you didn't have a data layer for this MVVM structure. For this, you need to create a class for data layer to do GRUD operations, and establish contact with this data service from ViewModel. More details please reference this article.
The class for data layer I wrote according to your description which contains how to read, update and delete data from mysql database is as follows:
public class Student
{
public int Student_id { get; set; }
public string Student_name { get; set; }
public string Student_mark { get; set; }
}
public class DataService
{
static string connectionString;
public static String Name = "Data Service.";
private static ObservableCollection<Student> _allStudents = new ObservableCollection<Student>();
public static ObservableCollection<Student> GetStudents()
{
try
{
string server = "127.0.0.1";
string database = "sakila";
string user = "root";
string pswd = "!QAZ2wsx";
connectionString = "Server = " + server + ";database = " + database + ";uid = " + user + ";password = " + pswd + ";SslMode=None;";
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
connection.Open();
MySqlCommand getCommand = connection.CreateCommand();
getCommand.CommandText = "SELECT * FROM student";
using (MySqlDataReader reader = getCommand.ExecuteReader())
{
while (reader.Read())
{
_allStudents.Add(new Student() { Student_id = reader.GetInt32(0), Student_name = reader.GetString(1), Student_mark = reader.GetString(2) });
}
}
}
}
catch (MySqlException sqlex)
{
// Handle it :)
}
return _allStudents;
}
public static bool InsertNewStudent(Student newStudent)
{
// Insert to the collection and update DB
try
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
connection.Open();
MySqlCommand insertCommand = connection.CreateCommand();
insertCommand.CommandText = "INSERT INTO student(student_id, student_name, student_mark)VALUES(#student_id, #student_name,#student_mark)";
insertCommand.Parameters.AddWithValue("#student_id", newStudent.Student_id);
insertCommand.Parameters.AddWithValue("#student_name", newStudent.Student_name);
insertCommand.Parameters.AddWithValue("#student_mark", newStudent.Student_mark);
insertCommand.ExecuteNonQuery();
return true;
}
}
catch (MySqlException sqlex)
{
return false;
}
}
public static bool UpdateStudent(Student Student)
{
try
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
connection.Open();
MySqlCommand insertCommand = connection.CreateCommand();
insertCommand.CommandText = "Update student Set student_name= #student_name, student_mark=#student_mark Where student_id =#student_id";
insertCommand.Parameters.AddWithValue("#student_id", Student.Student_id);
insertCommand.Parameters.AddWithValue("#student_name", Student.Student_name);
insertCommand.Parameters.AddWithValue("#student_mark", Student.Student_mark);
insertCommand.ExecuteNonQuery();
return true;
}
}
catch (MySqlException sqlex)
{
// Don't forget to handle it
return false;
}
}
public static bool Delete(Student Student)
{
try
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
connection.Open();
MySqlCommand insertCommand = connection.CreateCommand();
insertCommand.CommandText = "Delete from sakila.student where student_id =#student_id";
insertCommand.Parameters.AddWithValue("#student_id", Student.Student_id);
insertCommand.ExecuteNonQuery();
return true;
}
}
catch (MySqlException sqlex)
{
return false;
}
}
}
For updating the database in TwoWay binding way, we can implement is by invoking the data updating method in
PropertyChanged event as follows:
void Person_OnNotifyPropertyChanged(Object sender, PropertyChangedEventArgs e)
{
organization.Update((StudentViewModel)sender);
}
For the completed demo you can download here.

Best way to handle exception in ADO.Net repository pattern

i have design small repository pattern for ado.net. now i could not manage to handle exception proper way. i want to push error to calling environment if any occur. if no error occur then result set will be push to calling environment.
i have repository called AdoRepository which extend other repository classes like employee etc. we are calling employee repository function from mvc controller. so i want to push error to mvc controller from employee repository if any occur during data fetch, if no error occur then data will be sent to mvc controller. here is my full code. please have look and share the idea for best design. if possible paste rectified code here.
Base repository
public abstract class AdoRepository<T> where T : class
{
private SqlConnection _connection;
public virtual void Status(bool IsError, string strErrMsg)
{
}
public AdoRepository(string connectionString)
{
_connection = new SqlConnection(connectionString);
}
public virtual T PopulateRecord(SqlDataReader reader)
{
return null;
}
public virtual void GetDataCount(int count)
{
}
protected IEnumerable<T> GetRecords(SqlCommand command)
{
var reader = (SqlDataReader) null;
var list = new List<T>();
try
{
command.Connection = _connection;
_connection.Open();
reader = command.ExecuteReader();
while (reader.Read())
{
list.Add(PopulateRecord(reader));
}
reader.NextResult();
if (reader.HasRows)
{
while (reader.Read())
{
GetDataCount(Convert.ToInt32(reader["Count"].ToString()));
}
}
Status(false, "");
}
catch (Exception ex)
{
Status(true, ex.Message);
}
finally
{
// Always call Close when done reading.
reader.Close();
_connection.Close();
_connection.Dispose();
}
return list;
}
protected T GetRecord(SqlCommand command)
{
var reader = (SqlDataReader)null;
T record = null;
try
{
command.Connection = _connection;
_connection.Open();
reader = command.ExecuteReader();
while (reader.Read())
{
record = PopulateRecord(reader);
Status(false, "");
break;
}
}
catch (Exception ex)
{
Status(true, ex.Message);
}
finally
{
reader.Close();
_connection.Close();
_connection.Dispose();
}
return record;
}
protected IEnumerable<T> ExecuteStoredProc(SqlCommand command)
{
var reader = (SqlDataReader)null;
var list = new List<T>();
try
{
command.Connection = _connection;
command.CommandType = CommandType.StoredProcedure;
_connection.Open();
reader = command.ExecuteReader();
while (reader.Read())
{
var record = PopulateRecord(reader);
if (record != null) list.Add(record);
}
}
finally
{
// Always call Close when done reading.
reader.Close();
_connection.Close();
_connection.Dispose();
}
return list;
}
}
StudentRepository which extend base AdoRepository
-----------------------------------------------
public class StudentRepository : AdoRepository<Student>
{
public int DataCounter { get; set; }
public bool hasError { get; set; }
public string ErrorMessage { get; set; }
public StudentRepository(string connectionString)
: base(connectionString)
{
}
public IEnumerable<Student> GetAll()
{
// DBAs across the country are having strokes
// over this next command!
using (var command = new SqlCommand("SELECT ID, FirstName,LastName,IsActive,StateName,CityName FROM vwListStudents"))
{
return GetRecords(command);
}
}
public Student GetById(string id)
{
// PARAMETERIZED QUERIES!
using (var command = new SqlCommand("SELECT ID, FirstName,LastName,IsActive,StateName,CityName FROM vwListStudents WHERE Id = #id"))
{
command.Parameters.Add(new ObjectParameter("id", id));
return GetRecord(command);
}
}
public IEnumerable<Student> GetStudents(int StartIndex, int EndIndex, string sortCol, string sortOrder)
{
string strSQL = "SELECT * FROM vwListStudents WHERE ID >=" + StartIndex + " AND ID <=" + EndIndex;
strSQL += " ORDER BY " + sortCol + " " + sortOrder;
strSQL += ";SELECT COUNT(*) AS Count FROM vwListStudents";
var command = new SqlCommand(strSQL);
return GetRecords(command);
}
public override Student PopulateRecord(SqlDataReader reader)
{
return new Student
{
ID = Convert.ToInt32(reader["ID"].ToString()),
FirstName = reader["FirstName"].ToString(),
LastName = reader["LastName"].ToString(),
IsActive = Convert.ToBoolean(reader["IsActive"]),
StateID = Convert.ToInt32(reader["StateID"].ToString()),
StateName = reader["StateName"].ToString(),
CityID = Convert.ToInt32(reader["CityID"].ToString()),
CityName = reader["CityName"].ToString()
};
}
public override void GetDataCount(int count)
{
DataCounter = count;
}
public override void Status(bool IsError, string strErrMsg)
{
hasError = IsError;
ErrorMessage = strErrMsg;
}
}
calling StudentRepository from mvc controller like below way
public class StudentController : Controller
{
private StudentRepository _data;
public StudentController()
{
_data = new StudentRepository(System.Configuration.ConfigurationManager.ConnectionStrings["StudentDBContext"].ConnectionString);
}
// GET: Stuent
public ActionResult List(StudentListViewModel oSVm)
{
StudentListViewModel SVm = new StudentListViewModel();
SVm.SetUpParams(oSVm);
SVm.Students = _data.GetStudents(SVm.StartIndex, SVm.EndIndex, SVm.sort, oSVm.sortdir).ToList();
SVm.RowCount = _data.DataCounter;
return View("ListStudents",SVm);
}
}

I don't get the point of this:
catch (Exception ex)
{
Status(true, ex.Message);
}
Simply not catch the exception and let it bubble up to the caller who, according to you, will know to handle it. No callbacks necessary.
Storing retrieved data in instance state seems like a bad way to go. Rather, return an object with that data. That results in a more straight forward API and has less mutable state.
finally
{
reader.Close();
_connection.Close();
_connection.Dispose();
}
There is a better way to go about this: Wrap resources in a using statement. In particular, part ways with the superstitious double dispose pattern.

Let the caller deal with the exception making sure that you log a decent error message (showing all relevant fields). The Status class will annoy the hell out of support people as it swallows the stack trace and says nothing about the data which has caused the error. DB exceptions are often caused by malformed data so its important to have this data logged when things go wrong.
As an aside, your PopulateRecord and GetDataCount methods should be abstract as the base versions do nothing. Another dev could easily think they don't need to implement these methods and would be left with a class with useless PopulateRecord and GetDataCount methods.

Call multiple SQL Server stored procedures in a transaction

For usage in my current project I've created a class that allows me to call SQL Server async.
My code looks like this:
internal class CommandAndCallback<TCallback, TError>
{
public SqlCommand Sql { get; set; }
public TCallback Callback { get; set; }
public TError Error { get; set; }
}
class MyCodes:SingletonBase<MyCodes>
{
private static string _connString = #"Data Source=MyDB;Initial Catalog=ED;Integrated Security=True;Asynchronous Processing=true;Connection Timeout=0;Application Name=TEST";
private MyCodes() { }
public void SetSystem(bool production)
{
_connString =
string.Format(#"Data Source=MyDB;Initial Catalog={0};Integrated Security=True;Asynchronous Processing=true;Connection Timeout=0;Application Name=TEST", production ? "ED" : "TEST_ED");
}
public void Add(string newCode, Action<int> callback, Action<string> error)
{
var conn = new SqlConnection(_connString);
SqlCommand cmd = conn.CreateCommand();
cmd.CommandTimeout = 0;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = #"ADD_CODE";
cmd.Parameters.Add("#NEW", SqlDbType.NVarChar).Value = newCode;
cmd.Parameters.Add("#NewId", SqlDbType.Int).Direction = ParameterDirection.Output;
try
{
cmd.Connection.Open();
}
catch (Exception ex)
{
error(ex.ToString());
return;
}
var ar = new CommandAndCallback<Action<int>, Action<string>> { Callback = callback, Error = error, Sql = cmd };
cmd.BeginExecuteReader(Add_Handler, ar, CommandBehavior.CloseConnection);
}
private static void Add_Handler(IAsyncResult result)
{
var ar = (CommandAndCallback<Action<int>, Action<string>>)result.AsyncState;
if (result.IsCompleted)
{
try
{
ar.Sql.EndExecuteReader(result);
ar.Callback(Convert.ToInt32(ar.Sql.Parameters["#NewId"].Value));
}
catch (Exception ex)
{
ar.Error(ex.Message);
}
}
else
{
ar.Error("Error executing SQL");
}
}
public void Update(int codeId, string newCode, Action callback, Action<string> error)
{
var conn = new SqlConnection(_connString);
SqlCommand cmd = conn.CreateCommand();
cmd.CommandTimeout = 0;
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = #"UPDATE_CODE";
cmd.Parameters.Add("#CODE_ID", SqlDbType.Int).Value = codeId;
cmd.Parameters.Add("#NEW", SqlDbType.NVarChar).Value = newCode;
try
{
cmd.Connection.Open();
}
catch (Exception ex)
{
error(ex.ToString());
return;
}
var ar = new CommandAndCallback<Action, Action<string>> { Callback = callback, Error = error, Sql = cmd };
cmd.BeginExecuteReader(Update_Handler, ar, CommandBehavior.CloseConnection);
}
private static void Update_Handler(IAsyncResult result)
{
var ar = (CommandAndCallback<Action, Action<string>>)result.AsyncState;
if (result.IsCompleted)
{
try
{
ar.Sql.EndExecuteReader(result);
ar.Callback();
}
catch (Exception ex)
{
ar.Error(ex.Message);
}
}
else
{
ar.Error("Error executing SQL");
}
}
}
This may look like too much of code, but it lets me call it as so:
private void Add_Click(object sender, EventArgs e)
{
MyCodes.Instance.Add("Test",Success,Error)
}
private void Success(int newId)
{
MessageBox.Show(newId.ToString(), "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
private void Error(string error)
{
MessageBox.Show(error, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
Above code works just fine for me, I'm able to do every call async.
Problem that I have right now is to do multiple calls as transaction - I would like to update 2 codes and add one new.
Normally I would call update, then in success handler call second update, and in handler to second update I would call add that would return new id.
Something like:
-UPDATE CODE
|-UPDATE CODE
|-ADD CODE (only this one return something)
But I would like to call all of those as transaction, so if add code would break updates would rollback.
Question:
Is it possible to call multiple async queries as a transaction?
Can I call my above methods as transaction or do I must create separate method to call my procedures as one? (I would like to avoid this one because it's just copying the same code from one method to another)
I would like to add that I use .NET 3.5 so await and other nice features aren't an option.

string cnnString =WebConfigurationManager.ConnectionStrings["MyString"].ConnectionString;
SqlConnection cnn = new SqlConnection(cnnString);
SqlTransaction transaction;
cnn.Open();
transaction = cnn.BeginTransaction();
try
{
// Command Objects for the transaction
SqlCommand cmd1 = new SqlCommand("sproc1", cnn);
SqlCommand cmd2 = new SqlCommand("sproc2", cnn);
cmd1.CommandType = CommandType.StoredProcedure;
cmd2.CommandType = CommandType.StoredProcedure;
cmd1.Parameters.Add(new SqlParameter("#Param1", SqlDbType.NVarChar, 50));
cmd1.Parameters["#Param1"].Value = paramValue1;
cmd1.Parameters.Add(new SqlParameter("#Param2", SqlDbType.NVarChar, 50));
cmd1.Parameters["#Param2"].Value = paramValue2;
cmd2.Parameters.Add(new SqlParameter("#Param3", SqlDbType.NVarChar, 50));
cmd2.Parameters["#Param3"].Value = paramValue3;
cmd2.Parameters.Add(new SqlParameter("#Param4", SqlDbType.NVarChar, 50));
cmd2.Parameters["#Param4"].Value = paramValue4;
cmd1.ExecuteNonQuery();
cmd2.ExecuteNonQuery();
transaction.Commit();
}
catch (SqlException sqlEx)
{
transaction.Rollback();
}
finally
{
cnn.Close();
cnn.Dispose();
}

Yes, it is possible. Simply call SqlConnection.BeginTransaction before your first call. Make sure you assign the returned SqlTransaction object to each SqlCommand.Transaction in the chain and call SqlTransaction.Commit() at the end.

public class Command
{
public string sql { get; set; }
public CommandType cmdType { get; set; }
public Dictionary<string, object> parameter { get; set; } = null;
}
private Command insertInvoice(Invoice invoice)
{
try
{
Dictionary<string, object> parameterLocal = new Dictionary<string, object>();
parameterLocal.Add("p_customerId", invoice.customerId);
parameterLocal.Add("p_invoiceNo", invoice.invoiceNo);
parameterLocal.Add("p_invoiceDate", invoice.invoiceDate);
parameterLocal.Add("p_invoiceAmount", invoice.invoiceAmount);
parameterLocal.Add("p_withInvoice", invoice.withInvoice);
return (new Command { sql = "sp_insertInvoice", cmdType = CommandType.StoredProcedure, parameter = parameterLocal });
}
catch (Exception ex)
{
throw ex;
}
}
private Command insertInvoiceModel(InvoiceModel invoiceModel)
{
try
{
Dictionary<string, object> parameterLocal = new Dictionary<string, object>();
parameterLocal.Add("p_invoiceNo", invoiceModel.invoiceNo);
parameterLocal.Add("p_model", invoiceModel.model);
parameterLocal.Add("p_quantity", invoiceModel.quantity);
parameterLocal.Add("p_unitPrice", invoiceModel.unitPrice);
return (new Command { sql = "sp_insertInvoiceModel", cmdType = CommandType.StoredProcedure, parameter = parameterLocal });
}
catch (Exception ex)
{
throw ex;
}
}
List<Command> commandList = new List<Command>();
cmd = insertInvoice(invoicesave);
commandList.Add(cmd);
cmd = insertInvoiceModel(invoiceModelSave);
commandList.Add(cmd);
try
{
erplibmain.erpDac.runOleDbTransaction(commandList);
}
catch (Exception ex)
{
throw ex;
}
public void runOleDbTransaction(List<Command> commandList)
{
OleDbConnection erpConnection = new OleDbConnection(ErpDalMain.connectionstring);
erpConnection.Open();
OleDbCommand erpCommand = erpConnection.CreateCommand();
OleDbTransaction erpTrans;
// Start a local transaction
erpTrans = erpConnection.BeginTransaction();
// Assign transaction object for a pending local transaction
erpCommand.Connection = erpConnection;
erpCommand.Transaction = erpTrans;
try
{
foreach (Command cmd in commandList)
{
erpCommand.CommandText = cmd.sql;
erpCommand.CommandType = cmd.cmdType;
foreach (KeyValuePair<string, object> entry in cmd.parameter)
{
erpCommand.Parameters.AddWithValue(entry.Key, entry.Value);
}
erpCommand.ExecuteNonQuery();
erpCommand.Parameters.Clear();
}
erpTrans.Commit();
}
catch (Exception e)
{
try
{
erpTrans.Rollback();
}
catch (OleDbException ex)
{
if (erpTrans.Connection != null)
{
throw ex;
}
}
throw e;
}
finally
{
erpConnection.Close();
}
}