Select statement using OleDbCommand throws InvalidOperationException - c#

I need to find a record in C# but I get an InvalidOperationException:
public static Auto findAuto(int kfznr)
{
Auto retAuto = new Auto();
try
{
myOleDbConnection.Open();
string query = "SELECT * FROM Auto WHERE Auto.KFZNR = " + kfznr;
OleDbCommand select = new OleDbCommand();
select.Connection = myOleDbConnection;
select.CommandText = query;
OleDbDataReader reader = select.ExecuteReader();
while (reader.Read())
{
Auto at = new Auto(Convert.ToInt32(reader[0]), Convert.ToString(reader[1]), Convert.ToString(reader[2]));
retAuto = at;
}
}
catch (OleDbException e)
{
Console.WriteLine(e.ToString());
}
return retAuto;
}
I get the error in the while loop at the creation of the new Auto.
When I run the same query in the SQLDeveloper I get one record (take a look at the first screenshot) but in my C# program I get there is no data for my row/cell.
When I hover the reader I get the following image. It says that the reader has rows:
Hope that you can help me fix this problem.

You need to use reader.GetValue(0)
public static Auto findAuto(int kfznr)
{
Auto retAuto = new Auto();
try
{
myOleDbConnection.Open();
string query = "SELECT * FROM Auto WHERE Auto.KFZNR = " + kfznr;
OleDbCommand select = new OleDbCommand();
select.Connection = myOleDbConnection;
select.CommandText = query;
OleDbDataReader reader = select.ExecuteReader();
while (reader.Read())
{
Auto at = new Auto(Convert.ToInt32(reader.GetValue(0)), Convert.ToString(reader.GetValue(1)), Convert.ToString(reader.GetValue(2)));
retAuto = at;
}
}
catch (OleDbException e)
{
Console.WriteLine(e.ToString());
}
return retAuto;
}
Also wanted to add...you can access the reader values by column name as well using:
reader["ColumnName"]...don't forget the "" around the name of the column ;)
public static Auto findAuto(int kfznr)
{
Auto retAuto = new Auto();
try
{
myOleDbConnection.Open();
string query = "SELECT * FROM Auto WHERE Auto.KFZNR = " + kfznr;
OleDbCommand select = new OleDbCommand();
select.Connection = myOleDbConnection;
select.CommandText = query;
OleDbDataReader reader = select.ExecuteReader();
while (reader.Read())
{
Auto at = new Auto(Convert.ToInt32(reader["col1"]), Convert.ToString(reader["col2"]), Convert.ToString(reader["col3"]));
retAuto = at;
}
}
catch (OleDbException e)
{
Console.WriteLine(e.ToString());
}
return retAuto;
}

Related

C# How to Update/Change the specific letter/number of a string in database

I ask these question coz i really don't know how i'm gonna do that and is it possible to do that?
What i want is to update/change here for example STA-100418-100 in database values, update/change the 100 based on the user input, like 50 it will be STA-100418-50.
Here's the provided image to be more precise
As you can see on the image, there's a red line, if user update the quantity as 60, In Codeitem STA-100418-100 should be STA-100418-60
I really have no idea on how to do that. I hope someone would be able to help me
here's my code for updating the quantity
private void btn_ok_Click(object sender, EventArgs e)
{
using (var con = SQLConnection.GetConnection())
{
using (var selects = new SqlCommand("Update Product_Details set quantity = quantity - #Quantity where ProductID= #ProductID", con))
{
selects.Parameters.Add("#ProductID", SqlDbType.VarChar).Value = _view.txt_productid.Text;
selects.Parameters.Add("#Quantity", SqlDbType.Int).Value = Quantity;
selects.ExecuteNonQuery();
}
}
}
Here's the code to get that format in codeitems
string date = DateTime.Now.ToString("MMMM-dd-yyyy");
string shortdate = DateTime.Now.ToString("-MMddy-");
private void Quantity_TextChanged(object sender, EventArgs e)
{
Code.Text = Supplier.Text.Substring(0, 3) + shortdate + Quantity.Text;
}
Here's what I use to update SQL-Server
public static DataTable GetSqlTable(string sqlSelect)
{
string conStr = ConfigurationManager.ConnectionStrings["connString"].ConnectionString;
DataTable table = new DataTable();
SqlConnection connection = new SqlConnection(conStr);
try
{
connection.Open();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
if (connection.State != ConnectionState.Open)
{
return table;
}
SqlCommand cmd = new SqlCommand(sqlSelect, connection);
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
try
{
adapter.Fill(table);
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
throw;
}
connection.Close();
connection.Dispose();
return table;
}
public static void GetSqlNonQuery(string sqlSelect)
{
string newObject = string.Empty;
string strConn = ConfigurationManager.ConnectionStrings["connString"].ConnectionString;
SqlConnection connection = new SqlConnection(strConn);
connection.Open();
if (connection.State != ConnectionState.Open)
{
return;
}
try
{
SqlCommand cmd = new SqlCommand(sqlSelect, connection);
cmd.ExecuteNonQuery();
connection.Close();
connection.Dispose();
}
catch (Exception ex)
{
string x = ex.Message + ex.StackTrace;
throw;
}
}
Here's how to use it
DataTable dt = GetSqlTable("select Quantity from product where CodeItem = 'STA-100418-100'");
string strQuantity = dt.Rows[0]["Quantity"].ToString();
GetSqlNonQuery(string.Format("UPDATE product SET CodeItem = '{0}' WHERE = 'STA-100418-100'", strQuantity));
User will input everytime in the Quantity textbox, the textchanged event of Quantity will be hit and you will get new value everytime with the same date but with different quantity. So you can use the Code.Text to update the CodeDateTime value or you can use a global variable instead of Code.Text and use it to update the column.
string date = DateTime.Now.ToString("MMMM-dd-yyyy");
string shortdate = DateTime.Now.ToString("-MMddy-");
private void Quantity_TextChanged(object sender, EventArgs e)
{
Code.Text = Supplier.Text.Substring(0, 3) + shortdate + Quantity.Text;
}
using (var con = SQLConnection.GetConnection())
{
using (var selects = new SqlCommand("Update Product_Details set quantity = quantity - #Quantity, CodeItem = #Code where ProductID= #ProductID", con))
{
selects.Parameters.Add("#ProductID", SqlDbType.VarChar).Value = _view.txt_productid.Text;
selects.Parameters.Add("#Quantity", SqlDbType.Int).Value = Quantity;
selects.Parameters.Add("#Code", Code.Text);
}
}
as I understand it you need MSSQL String Functions
SELECT rtrim(left(Codeitem,charindex('-', Codeitem))) + ltrim(str(Quantity)) FROM ...
For detailed information
Using MySql, Substring the code item and then concatenate the quantity.
UPDATE Product_Details SET quantity = #quantity,CodeIem = CONCAT(SUBSTR(#code,1,11),#quantity) WHERE ProductID= #ProductID

SQLDataReader bugging while using .Nest() or .Read()

I'm retrieving some information from an MSSQL via SQLDataReader, but while debugging it I notice in some cases the reader clears the result view with the error "Enumeration yielded no results" see the screenshot Before Running passing Read(),
After passing read()
this is my code,the error happens on getActiveUsers() method.
getDatabases() works just fine. could someone help me? cheers
public partial class automation : System.Web.UI.Page
{
SqlConnection con;
static List<ActiveUsers> activeUsers = new List<ActiveUsers>();
protected void Page_Load(object sender, EventArgs e)
{
ASPxGridView1.DataSource = activeUsers.ToList();
}
public List<ActiveUsers> getDatabases()
{
//passing query
string SqlQuery = "SELECT [WorkspaceName],[MaConfig_Customers].Name FROM [MaConfig_CustomerDatabases] INNER JOIN [MaConfig_Customers] ON [MaConfig_CustomerDatabases].CustomerId = [MaConfig_Customers].CustomerId where [MaConfig_Customers].Status = 0";
//creating connection
string sqlconn = ConfigurationManager.ConnectionStrings["MaxLiveConnectionString"].ConnectionString;
con = new System.Data.SqlClient.SqlConnection(sqlconn);
var cmd = new SqlCommand(SqlQuery, con);
con.Open();
SqlDataReader reader = cmd.ExecuteReader();
List<ActiveUsers> results = new List<ActiveUsers>();
if (reader.Read())
{
while (reader.Read())
{
ActiveUsers company = new ActiveUsers();
company.DatabaseName = String.Format("{0}", reader["WorkspaceName"]);
company.ClientName = String.Format("{0}", reader["Name"]);
results.Add(company);
}
}
con.Close();
return results;
}
public void getActiveUsers()
{
activeUsers.Clear();
List<ActiveUsers> Databases= getDatabases();
SqlConnection conn = new SqlConnection();
string SqlQuery = "select [disabled], [ADMN_Users1].[Record_Id] ,[ADMN_Users].[User_Id] from admn_Users1 inner join [ADMN_Users] on [ADMN_Users1].[record_Id] = [ADMN_Users].[Record_Id] Where [disabled] & 0x2 = 0 ";
for (int i = 0;i < Databases.Count;i++)
{
conn.ConnectionString =
"Data Source=MAXSQLCLUS01;" +
"Initial Catalog=" + Databases[i].ToString()+";"+
"User id=sa;" +
"Password=Max1m1zer;";
var cmd = new SqlCommand(SqlQuery, conn);
conn.Open();
SqlDataReader reader = cmd.ExecuteReader();
int NumberOfUsersCounter = 0 ;
//TODO Select Enabled users
if (reader.Read())
{
while (reader.Read())
{
string user = String.Format("{0}", reader["User_Id"]);
//logic to remove system users
if (user.Equals("master", StringComparison.CurrentCultureIgnoreCase))
{
}
else
if (user.Equals("emailuser", StringComparison.CurrentCultureIgnoreCase))
{
}
else
if (user.Equals("webuser", StringComparison.CurrentCultureIgnoreCase))
{
}
else
{
NumberOfUsersCounter++;
}
}
ActiveUsers newEntry = new ActiveUsers();
newEntry.NumberActiveUsers = NumberOfUsersCounter.ToString();
newEntry.DatabaseName = Databases[i].DatabaseName.ToString();
newEntry.ClientName = Databases[i].ClientName.ToString();
activeUsers.Add(newEntry);
}
conn.Close();
//Add to ActiveUsers list
}
ASPxGridView1.AutoGenerateColumns = true;
ASPxGridView1.DataSource = activeUsers.ToList();
ASPxGridView1.DataBind();
}
protected void ASPxButton1_Click(object sender, EventArgs e)
{
getActiveUsers();
}
protected void btnExportExcel_Click(object sender, EventArgs e)
{
ASPxGridView1.DataBind();
ASPxGridViewExporter1.Landscape = true;
ASPxGridViewExporter1.FileName = "User Count Report";
ASPxGridViewExporter1.WriteXlsToResponse();
}
}
}
if (reader.Read())
{
while (reader.Read())
{
ActiveUsers company = new ActiveUsers();
company.DatabaseName = String.Format("{0}", reader["WorkspaceName"]);
company.ClientName = String.Format("{0}", reader["Name"]);
results.Add(company);
}
}
use this
if (reader.HasRows)
{
while (reader.Read())
{
ActiveUsers company = new ActiveUsers();
company.DatabaseName = String.Format("{0}", reader["WorkspaceName"]);
company.ClientName = String.Format("{0}", reader["Name"]);
results.Add(company);
}
}
your if Condition is wrong
if(reader.Read()) ==> is Wrong
Read() is not return boolean Value
use HasRows to check rows in SQLDataReader
You are skipping the first result. if (reader.Read()) { while(reader.Read()) {.... Remove the enclosing if, all it does is see if there is a row and retrieve it but then you do not read it, instead you do it again in the if so the first result is always discarded.
public List<ActiveUsers> getDatabases()
{
//passing query
string SqlQuery = "SELECT [WorkspaceName],[MaConfig_Customers].Name FROM [MaConfig_CustomerDatabases] INNER JOIN [MaConfig_Customers] ON [MaConfig_CustomerDatabases].CustomerId = [MaConfig_Customers].CustomerId where [MaConfig_Customers].Status = 0";
//creating connection
string sqlconn = ConfigurationManager.ConnectionStrings["MaxLiveConnectionString"].ConnectionString;
using(con = new System.Data.SqlClient.SqlConnection(sqlconn))
using(var cmd = new SqlCommand(SqlQuery, con))
{
con.Open();
using(SqlDataReader reader = cmd.ExecuteReader())
{
List<ActiveUsers> results = new List<ActiveUsers>();
while (reader.Read())
{
ActiveUsers company = new ActiveUsers();
company.DatabaseName = reader.GetString(0);
company.ClientName = reader.GetString(1);
results.Add(company);
}
}
}
return results;
}
Side notes:
company.DatabaseName = String.Format("{0}", reader["WorkspaceName"]) would be better written as company.DatabaseName = reader.GetString(0). The same goes for the next line. No need to use string.Format and you are specifying the columns and order in the query so use the ordinal index so get the native value.
I would recommend you wrap the SqlConnection and SqlDataReader in using blocks to ensure they are closed/disposed after use even in the event of an exception.

ProductInsert() does not exist in current context

protected void Btn_CheckOut_Click(object sender, EventArgs e)
{
int result = 0;
Payment user = new Payment(txt_CardNumber.Text, txt_CardHolderName.Text, txt_ExpirationDate.Text, txt_Cvv.Text);
result = ProductInsert();
/* Session["CardNumber"] = txt_CardNumber.Text;
Session["CardHolderName"] = txt_CardHolderName.Text;
Session["ExpirationDate"] = txt_ExpirationDate.Text;
Session["Cvv"] = txt_Cvv.Text;*/
Response.Redirect("Payment Sucessful.aspx");
}
public int ProductInsert()
{
int result = 0;
string queryStr = "INSERT INTO CustomerDetails(CardNumber, CardHolderName, ExpirationDate, Cvv)"
+ "values (#CardNumber,#CardHolderName, #ExpirationDate, #Cvv)";
try
{
SqlConnection conn = new SqlConnection(connStr);
SqlCommand cmd = new SqlCommand(queryStr, conn);
cmd.Parameters.AddWithValue("#CardNumber", this.CardNumber);
cmd.Parameters.AddWithValue("#CardHolderName", this.CardHolderName);
cmd.Parameters.AddWithValue("#ExpirationDate", this.ExpirationDate);
cmd.Parameters.AddWithValue("#Cvv", this.Cvv);
conn.Open();
result += cmd.ExecuteNonQuery(); // Returns no. of rows affected. Must be > 0
conn.Close();
return result;
}
catch (Exception ex)
{
return 0;
}
}
}
I am trying to store credit card informations into database. I have created a productInsert() method and now I am trying to insert whatever values into the database.
This code is giving the error:
ProductInsert() does not exist in current context

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

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

Image.MemoryStream : Parameter not valid

When I'm trying to retrieve my image by combo box there show the massage . Parameter not valid
I was try many way but problem is same ..
Every time I run the code below, I get same massage.
private void cBoxSearch_SelectedIndexChanged(object sender, EventArgs e)
{
try
{
con = ConnectionController.GetInstance().GetConnection();
con.Open();
com = new SQLiteCommand("SELECT * FROM Stock WHERE ProductName = '" + cBoxSearch.Text + "' ", con);
myReader = com.ExecuteReader();
product prod = new product();
while (myReader.Read())
{
prod.proid = myReader[0].ToString();
prod.prodname = myReader[1].ToString();
prod.proMdl = myReader[2].ToString();
prod.serialN = myReader[3].ToString();
prod.byibgPr = myReader[4].ToString();
prod.sellPr = myReader[5].ToString();
prod.quantity = myReader[6].ToString();
tbxProductID.Text = prod.proid;
tbxName.Text =prod.prodname;
tbxModel.Text = prod.proMdl;
tbxserial.Text = prod.serialN;
tbxbyingprice.Text = prod.byibgPr;
tbxSellingprice.Text = prod.sellPr;
tbxQuantity.Text = prod.quantity;
prod.imgg = (byte[])(myReader[7] );
if (prod.imgg == null)
{
pBX.Image = null;
}
else
{
MemoryStream mstrm = new MemoryStream(prod.imgg);
Bitmap bmp = new Bitmap(mstrm);
}
}
con.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
com.Cancel();
con.Close();
}
Try to consult this question:
convert binary to bitmap using memory stream
Also, it might depend on DBType of the 8th column of the query.

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