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Using Database Change Notification on multiple tables

I am developing an application in C# where I'm trying to use Oracle Database Change Notification.
When I'm using DCN for one table, everything is working as expected but when I am trying to use two tables, I get the following error: "Attempted to read or write protected memory. This is often an indication that other memory is corrupt", on the line cmd.ExecuteNonQuery();
Here is the code:
string sql = "select rowid, first_name, last_name, salary from employees where employee_id = :1" +
"select country_id, country_name, region_id from countries where country_id = :2";
string constr = "User Id=hr;Password=Parola_007;Data Source=ORCL;Pooling=false";
con = new OracleConnection(constr);
con.Open();
OracleCommand cmd = new OracleCommand(sql, con);
OracleParameter p_id = new OracleParameter();
p_id.OracleDbType = OracleDbType.Decimal;
p_id.Value = 149;
OracleParameter p_id2 = new OracleParameter();
p_id2.OracleDbType = OracleDbType.Varchar2;
p_id2.Value = "BE";
cmd.BindByName = true;
cmd.Parameters.Add(p_id);
cmd.Parameters.Add(p_id2);
OracleDependency dep = new OracleDependency(cmd);
cmd.Notification.IsNotifiedOnce = false;
dep.OnChange += new OnChangeEventHandler(OnDatabaseNotification);
cmd.ExecuteNonQuery();
public static void OnDatabaseNotification(object src, OracleNotificationEventArgs args)
{
string sql = "select rowid, first_name, last_name, salary from employees where rowid = :1" +
"select rowid, country_id, country_name, region from countries where rowid = :2";
OracleParameter p_rowid = new OracleParameter();
p_rowid.Value = args.Details.Rows[0]["rowid"];
OracleParameter p_rowid2 = new OracleParameter();
p_rowid2.Value = args.Details.Rows[1]["rowid"];
OracleCommand cmd = con.CreateCommand();
cmd.CommandText = sql;
cmd.BindByName = true;
cmd.Parameters.Add(p_rowid);
cmd.Parameters.Add(p_rowid2);
OracleDataReader dr = cmd.ExecuteReader();
dr.Read();
Console.WriteLine();
Console.WriteLine("Database Change Notification received!");
DataTable changeDetails = args.Details;
Console.WriteLine("Resource {0} has changed.", changeDetails.Rows[0]["ResourceName"]);
Console.WriteLine("Resource {1} has changed.", changeDetails.Rows[1]["ResourceName"]);
dr.Dispose();
cmd.Dispose();
p_rowid.Dispose();
}
Am I doing something wrong?
Thanks.

1: you cannot do 2 sql in 1 command.
2: You can use the table trigger in oracle to check the changed table data. All changes should be logged in a table and only need to be query from that table.
sorry for my english

MS Access Update Query Not Working

I can't Figure out what is wrong with the query, but it is not updating any value in the Table
string qry = "UPDATE Stock SET Itemname=#n,Unit=#u,Price=#p,Tax=#t,Balance=#b,Status=#s Where Sid=#sid";
OleDbCommand ocmd = new OleDbCommand(qry,BBC);
ocmd.Parameters.AddWithValue("#n", name);
ocmd.Parameters.AddWithValue("#u", unit);
ocmd.Parameters.AddWithValue("#p", price);
ocmd.Parameters.AddWithValue("#t", tax);
ocmd.Parameters.AddWithValue("#b", balance);
ocmd.Parameters.AddWithValue("#s", status);
ocmd.Parameters.AddWithValue("#sid", sid);
ocmd.ExecuteNonQuery();
Price,Tax and Balance are Decimal values.
I did debug and its working fine but just not updating the value.

set the type of each parameter and execute the query.
List<OleDbParameter> paramList = new List<OleDbParameter>();
OleDbParameter param = new OleDbParameter("#param", OleDbType.TypeName);
param.Value = value;
paramList.Add(param);
ocmd.Parameters.AddRange(paramArray);

I think this will do it for you.
string ConnString = #"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=\\your_path_here\test.accdb";
using(OleDbConnection conn = new OleDbConnection(ConnString ))
using(OleDbCommand cmd = conn.CreateCommand())
{
cmd.CommandText = # "UPDATE Stock SET Itemname=#n,Unit=#u,Price=#p,Tax=#t,Balance=#b,Status=#s Where Sid=#sid";
cmd.Parameters.AddWithValue("#n", txtItemName.Text);
cmd.Parameters.AddWithValue("#u", txtUnit.Text);
cmd.Parameters.AddWithValue("#p", Convert.ToDecimal(txtPrice.Text));
cmd.Parameters.AddWithValue("#t", Convert.ToDecimal(txtTax.Text));
cmd.Parameters.AddWithValue("#b", Convert.ToDecimal(txtBalance.Text));
cmd.Parameters.AddWithValue("#s", txtStatus.Text);
cmd.Parameters.AddWithValue("#sid", txtSID.Text);
conn.Open();
int rowsAffected = cmd.ExecuteNonQuery();
conn.Close();
}

Update table record from sqlcommand

I have this situation: in DataEntryForm I have a dropdownlist, where user selects a letter number, and according to that inserts other related data.
I plan to change letter's status in other table by choosing in dropdownlist automatically.
I am using this code:
SqlParameter answertoparam = new SqlParameter("answerto", ansTo);
string commandText = "update IncomeLetters set IncomeLetters.docState_ID ='2' where income_number=('" + ansTo + "' )";
SqlCommand findincomelett = new SqlCommand(commandText, conn);
comm.Parameters.Add(answertoparam);
conn.Open();
findincomelett.ExecuteNonQuery();
comm.ExecuteNonQuery();
Unfortunately, the result is nothing.
Server is not giving error, and it simply refreshes the page that is it.

In your posted code, you are passing the SqlParameter as well as passing the value as raw data. Do either of one and preferably pass it as SqlParameter like
SqlParameter answertoparam = new SqlParameter("answertoparam", ansTo);
string commandText = "update IncomeLetters set IncomeLetters.docState_ID = '2' where income_number = #answertoparam";
SqlCommand findincomelett = new SqlCommand(commandText, conn);
findincomelett.Parameters.Add(answertoparam);
conn.Open();
findincomelett.ExecuteNonQuery();
Moreover, you have two SqlCommand object in place and calling two ExecuteNonQuery() on them. correct that ... see below
SqlCommand findincomelett = new SqlCommand(commandText, conn); --1
comm.Parameters.Add(answertoparam); --2
conn.Open();
findincomelett.ExecuteNonQuery(); --1
comm.ExecuteNonQuery(); --2

As far as I understand, the issue is that the correct IncomeLetters.docState_ID is not updated to '2'.
You may want to debug and see what value you are getting in :
string ansTo = ddlAnswerTo.SelectedItem.Value;
The record in the database that you are expecting to be updated may not have the record that satisfies the where clause 'income_number = #answertoparam'

I would like to bring you here full code of the page.
Idea is: I have page for enrollment. I am passing data to DB through stored procedure (DataInserter).
Problem is here: during enrollment, user selects from dropdownlist number of the letter he would like to answer to, and in the end, the status of the letter on other table of DB (IncomeLetters.tbl), would change from "pending"('1') to "issued" ('2').
I guess, I could clear my point to you and thank you for your support!
protected void Button1_Click(object sender, EventArgs e)
{
SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["MaktubhoConnectionString2"].ConnectionString);
using (SqlCommand comm = new SqlCommand("DataInserter", conn))
{
comm.CommandType = CommandType.StoredProcedure;
comm.Connection = conn;
SqlParameter employeeparam = new SqlParameter("EmployeeSentIndex", int.Parse(ddlemployee.SelectedItem.Value));
SqlParameter doctypeparam = new SqlParameter("doctype_ID", int.Parse(ddldoctype.SelectedItem.Value));
SqlParameter doccharparam = new SqlParameter("docchar_ID", int.Parse(ddldocchar.SelectedItem.Value));
SqlParameter authorityparam = new SqlParameter("authority", txtauthority.Text);
SqlParameter subjectparam = new SqlParameter("subject", txtsubject.Text);
DateTime dt = DateTime.Now;
string todasdate = dt.ToString("d", CultureInfo.CreateSpecificCulture("de-DE"));
SqlParameter entrydateparam = new SqlParameter("entrydate", todasdate);
string Pathname = "UploadImages/" + Path.GetFileName(FileUpload1.PostedFile.FileName);
SqlParameter imagepathparam = new SqlParameter("image_path", Pathname);
SqlParameter loginparam = new SqlParameter("login", "jsomon");
comm.Parameters.Add(employeeparam);
comm.Parameters.Add(doctypeparam);
comm.Parameters.Add(doccharparam);
comm.Parameters.Add(authorityparam);
comm.Parameters.Add(subjectparam);
comm.Parameters.Add(entrydateparam);
comm.Parameters.Add(imagepathparam);
comm.Parameters.Add(loginparam);
comm.Parameters.Add("#forlabel", SqlDbType.VarChar, 100);
comm.Parameters["#forlabel"].Direction = ParameterDirection.Output;
FileUpload1.SaveAs(Server.MapPath("~/UploadImages/" + FileUpload1.FileName));
string ansTo = ddlAnswerTo.SelectedItem.Value;
SqlParameter answertoparam = new SqlParameter("answertoparam", ansTo);
string commandText = "update IncomeLetters set IncomeLetters.docState_ID = '2' where income_number = #answertoparam";
SqlCommand findincomelett = new SqlCommand(commandText, conn);
findincomelett.Parameters.Add(answertoparam);
conn.Open();
findincomelett.ExecuteNonQuery();
comm.ExecuteNonQuery();
lblresult.Visible = true;
Image1.Visible = true;
lblresult.Text = "Document number:";
lblnumber.Visible = true;
lblnumber.Text = (string)comm.Parameters["#forlabel"].Value; ;
conn.Close();
}
txtauthority.Text = "";
txtsubject.Text = "";
}

DataRoutines not creating data in Access Database

today, I am trying to use DataRoutines to insert some values into my Access Database. However, it did not work as well as there were no records created. Does anyone know what's wrong with my code?
This is my DataRoutines (dataroutines2) file
public void CreateRecs(string strUserId)
{
OleDbConnection mDB = new OleDbConnection();
mDB.ConnectionString = "Provider = Microsoft.ACE.OLEDB.12.0;Data source="
+ Server.MapPath("~/App_Data/webBase.accdb");
OleDbCommand cmd; OleDbDataReader rdr;
string strSql;
string strOFlag = "F";
// check to see if there is an active order record
strSql = "SELECT eStatus FROM enrolInfo WHERE eUserId = #UserId "
+ "ORDER BY eEnrolNo DESC;";
cmd = new OleDbCommand(strSql, mDB);
cmd.Parameters.Add("#UserId", OleDbType.Char).Value = strUserId;
mDB.Open();
rdr = cmd.ExecuteReader();
Boolean booRows = rdr.HasRows;
if (booRows) //when booRows is true, there are order records for the user
{
rdr.Read();
if ((string)rdr["eStatus"] != "Ordering") //status of an active order is "Ordering"
{
strOFlag = "M"; //"T" means there is a need to create a new Orders record
}
else { strOFlag = "M"; }
mDB.Close();
if (strOFlag == "M")
{
//insert a new order record
string strStatus = "Ordering";
strSql = "INSERT INTO enrolInfo (eUserId, eStatus) VALUES (#UserId, #Status)";
cmd = new OleDbCommand(strSql, mDB);
cmd.Parameters.AddWithValue("#UserId", strUserId);
cmd.Parameters.AddWithValue("#Status", strStatus);
mDB.Open();
cmd.ExecuteNonQuery();
mDB.Close();
}
//get back order No - this order no is needed when the user buys an item
strSql = "SELECT eEnrolNo FROM enrolInfo WHERE eUserId = #UserId "
+ "ORDER BY eEnrolNo DESC;";
cmd = new OleDbCommand(strSql, mDB);
cmd.Parameters.Add("#UserId", OleDbType.Char).Value = strUserId;
mDB.Open();
rdr = cmd.ExecuteReader();
rdr.Read();
Session["tOrderNo"] = rdr["eEnrolNo"]; //store the active order no in the sOrderNo
mDB.Close();
return;
}
}
This is the code that will route the solution to the DataRoutines file in my Register Page
//prepare Session variables for newly register customer
Session["sFlag"] = "M";
Session["tUserId"] = (string)txtUserId.Text;
Session["tName"] = (string)txtName.Text;
Session["tAddress"] = (string)txtAddress.Text;
Session["tTel"] = (string)txtTel.Text;
Session["tEmail"] = (string)txtEmail.Text;
String strUserId = (string)Session["tUserId"];
DataRoutines2 DRObject = new DataRoutines2();
DRObject.CreateRecs(strUserId);
Thanks for your help

How to assign default value in a parameter?

I have the codes below that will display data from access database into textboxes of another form.
item items = new item();
Add_Order addorder = new Add_Order();
OleDbCommand cmd = new OleDbCommand("Select * from tblItems WHERE ItemName = #Item", connection);
cmd.Parameters.AddWithValue("#Item", items.ItemName1);
cmd.Connection = connection;
connection.Open();
cmd.ExecuteNonQuery();
cmd.Parameters.AddWithValue("#ItemID", addorder.tbItemID.Text);
cmd.Parameters.AddWithValue("#ItemName", addorder.tbName.Text);
cmd.Parameters.AddWithValue("#ItemPrice", addorder.tbPrice.Text);
OleDbDataReader read = cmd.ExecuteReader();
while (read.Read())
{
addorder.tbItemID.Text = read[0].ToString();
addorder.tbName.Text = read[1].ToString();
addorder.tbPrice.Text = read[2].ToString();
}
addorder.ShowDialog();
connection.Close();
the error says that
Parameter #Item has no default value
But I already assigned the value of #Item in this line
cmd.Parameters.AddWithValue("#Item", items.ItemName1);

I found some mistakes, you are retrieving some items. Then, Why you are using ExecuteNonquery() and some other parameters. Simply try this
cmd.Connection = connection;
connection.Open();
OleDbCommand cmd = new OleDbCommand("Select * from tblItems WHERE ItemName = #Item", connection);
cmd.Parameters.AddWithValue("#Item", items.ItemName1);
OleDbDataReader read = cmd.ExecuteReader();
while (read.Read())
{
addorder.tbItemID.Text = read[0].ToString();
addorder.tbName.Text = read[1].ToString();
addorder.tbPrice.Text = read[2].ToString();
}
connection.Close();
Make sure that items.ItemName1 has a valid entry. You can verify this by simply passing some values manually as
cmd.Parameters.AddWithValue("#Item", "some text");

Try this one:
cmd.Parameters.AddWithValue("#Item", OleDbType.VarChar).Value = items.ItemName1;
And why are you using this again after ExecuteNonQuery()..?
cmd.Parameters.AddWithValue("#ItemID", addorder.tbItemID.Text);
cmd.Parameters.AddWithValue("#ItemName", addorder.tbName.Text);
cmd.Parameters.AddWithValue("#ItemPrice", addorder.tbPrice.Text);

cmd.Parameters.Add(new OleDbParameter("item", OleDbType.VarChar, 32, "Item").Value = items.ItemName1;
^^^^^^^^^^^^^^^^^^
the point is to construct Parameter()