system.invalidcastexception specified cast is not valid. c#

Question

Hi to all

Sir i have a problem 'system.invalidcastexception specified cast is not valid. c#"

sqlConnection.Open();

SqlCommand command = new SqlCommand(query, sqlConnection);

int i = (int)command.ExecuteScalar();

sqlConnection.Close();

Please solve my problem

Regards

NagaRaju T

Iftikar Hussain · Answer

try like this SELECT Max(cast(SUBSTRING(OrderNo275) as int)) as LastOrderNo FROM PurchaseVendor Regards Iftikar

NAGARAJU TAMADA · Answer

Very Very Thanks SirIts Working fine now. Thanks for your efforts on my code Regards Nagaraju T

NAGARAJU TAMADA · Answer

This value from database. first orderNo was created successfully.but exception raises while getting the second OrderNo. I think exception raises in this conversion i = Convert.ToInt32(sqlDataReader[LastOrderNo]);

Sanjeeb Lenka · Answer

System.Data.SqlClient.SqlException (0x80131904): Conversion failed when converting the varchar value 'QIEPL/2013/Head Office/PO/00001' to data type int. Exception Occures at this line: while (sqlDataReader.Read()) from where you are getting this value 'QIEPL/2013/Head Office/PO/00001'

NAGARAJU TAMADA · Answer

sory sir its not working still same exception occured

Sanjeeb Lenka · Answer

try like this by separating the code it may help you: int i = 0; int j = 1; string query = SELECT Max(cast(OrderNo as int)) as LastOrderNo FROM PurchaseVendor; DateTime currentDate = DateTime.Parse(dateString); int year = currentDate.Year; string branchName = comboSite.Text; SqlDataReader sqlDataReader = vendor.DataSourceClass.getSqlDataReader(query); while (sqlDataReader.Read()) { if (sqlDataReader[LastOrderNo].ToString() != string.Empty) { i = Convert.ToInt32(sqlDataReader[LastOrderNo]); } } if (i > 0) { j = i + 1; txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } else { txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); }

NAGARAJU TAMADA · Answer

thanks for u reply sir Here first orderNo created successfullybut exception occures while loading the second orderNo System.Data.SqlClient.SqlException (0x80131904): Conversion failed when converting the varchar value 'QIEPL/2013/Head Office/PO/00001' to data type int. Exception Occures at this line: while (sqlDataReader.Read())

Sanjeeb Lenka · Answer

try this code: string query = SELECT Max(cast(OrderNo as int)) as LastOrderNo FROM PurchaseVendor; DateTime currentDate = DateTime.Parse(dateString); int year = currentDate.Year; string branchName = comboSite.Text; SqlDataReader sqlDataReader = vendor.DataSourceClass.getSqlDataReader(query); while (sqlDataReader.Read()) { int i=0; if (sqlDataReader[LastOrderNo].ToString() != string.Empty) { i = Convert.ToInt32(sqlDataReader[LastOrderNo]); } int j = 1; if (i > 0) { j = i + 1; txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } else { txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } }

Iftikar Hussain · Answer

can you provide me data from this table with table design? Regards Iftikar

NAGARAJU TAMADA · Answer

yes siri didn't get any value from dbthat's why the problem occurs.its working on count()but it failed on max() please check it sir

Sanjeeb Lenka · Answer

what the problem you are getting. if the null value coming from database it will not enter into that and show msg no order found.

Iftikar Hussain · Answer

are you getting no output for the below query? SELECT Max(cast(OrderNo as int)) as LastOrderNo FROM PurchaseVendor Regards Iftikar

NAGARAJU TAMADA · Answer

Its not working properly sir

Iftikar Hussain · Answer

Yes Please pass proper value to your query and execute and check. Regards Iftikar

Sanjeeb Lenka · Answer

try this code: string query = SELECT Max(cast(OrderNo as int)) as LastOrderNo FROM PurchaseVendor; DateTime currentDate = DateTime.Parse(dateString); int year = currentDate.Year; string branchName = comboSite.Text; SqlDataReader sqlDataReader = vendor.DataSourceClass.getSqlDataReader(query); while (sqlDataReader.Read()) { if (sqlDataReader[LastOrderNo].ToString() != string.Empty) { int i = Convert.ToInt32(sqlDataReader[LastOrderNo]); int j = 1; if (i > 0) { j = i + 1; txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } else { txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } } }

NAGARAJU TAMADA · Answer

Its gets null value sir Thats Why this cant get exact value into the integer variable

Sanjeeb Lenka · Answer

Hi execute this query in database and check its giving the correct out put or not

NAGARAJU TAMADA · Answer

Exception Raises System.InvalidCastException: Object cannot be cast from DBNull to other types.

Sanjeeb Lenka · Answer

hi try this query SELECT Max(cast(OrderNo as int)) as LastOrderNo FROM PurchaseVendor or you can try this SELECT MAX(CONVERT(INTOrderNo)) as LastOrderNo FROM PurchaseVendor

NAGARAJU TAMADA · Answer

Thanks for your reply sir Its datatype is Varchar(50) and its holds primarykey defination

Sanjeeb Lenka · Answer

what is the datatype of order no Column in database. int or varchar

NAGARAJU TAMADA · Answer

Thanks for your reply sir. If there is data in database the query works well.But The exception raises if the db empty. my orderno in series like QIEPL/2013/branchName /PO/00001 QIEPL/2013/branchName /PO/00002 QIEPL/2013/branchName /PO/00003 .............................. my original code is try { string query = SELECT Count(OrderNo) as LastOrderNo FROM PurchaseVendor; DateTime currentDate = DateTime.Parse(dateString); int year = currentDate.Year; string branchName = comboSite.Text; SqlDataReader sqlDataReader = vendor.DataSourceClass.getSqlDataReader(query); while (sqlDataReader.Read()) { int i = Convert.ToInt32(sqlDataReader[LastOrderNo]); int j = 1; if (i > 0) { j = i + 1; txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } else { txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } } } its works fine.but iwant to use Max() instead of Count() in Sql query. Plz solve my problem.I tired alot but i didn't get answer. Regards Nagaraju T

Sanjeeb Lenka · Answer

What are the values are present in OrderNo column in database. give some sample data

NAGARAJU TAMADA · Answer

Thanks for ur reply. Iam expecting integer Values 0123. but i didn't get those values. If iam using Count() instead Max()its works well.The problem occurs when i used Max(0) in the query. Regards NagaRaju

Sanjeeb Lenka · Answer

what is the expected value you are getting for i from database;

NAGARAJU TAMADA · Answer

k Sorry Val = Convert.ToInt32(i); In this line the exception raised

Sanjeeb Lenka · Answer

hi check once your post there is no highlighted line.

NAGARAJU TAMADA · Answer

Thanks for ur reply sir SqlConnection sqlConnection = vendor.DataSourceClass.getSqlConnection(); string query = SELECT MAX(OrderNo) as LastOrderNo FROM PurchaseVendor; SqlCommand cmd = new SqlCommand(query sqlConnection); sqlConnection.Open(); object i = cmd.ExecuteScalar() as string; sqlConnection.Close(); DateTime currentDate = DateTime.Parse(dateString); int year = currentDate.Year; string branchName = comboSite.Text; int j = 1; int Val = 0; if (!Convert.IsDBNull(i)) { Val = Convert.ToInt32(i); j = Val + 1; txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } else { txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } } Please Check The Heighlighted line sir . Thanks & Regards Nagaraju T

Vulpes · Answer

On what line is that exception being thrown?

NAGARAJU TAMADA · Answer

Thank u sir Exception raised:System.FormatException: Input string was not in a correct format. Please solve my problem sir Regards Nagaraju T

Riyaz Akhtar · Answer

try this code: sqlConnection.Open(); SqlCommand command = new SqlCommand(query sqlConnection); object i = command.ExecuteScalar(); sqlConnection.Close(); int intVal=0; if (!Convert.IsDBNull(i)) { intVal = (int) i; }

NAGARAJU TAMADA · Answer

Thanks for ur reply sir here the exception raised:System.InvalidCastException: Specified cast is not valid. Regards NagaRaju T

Riyaz Akhtar · Answer

try this code: sqlConnection.Open(); SqlCommand command = new SqlCommand(query sqlConnection); string i = command.ExecuteScalar() as string; sqlConnection.Close(); if (i==null) { MessageBox.Show(No record found); } else { intVal = Convert.ToInt32(i); }

Vulpes · Answer

Try: object o = command.ExecuteScalar(); int i = -1; // some value to indicate no data if( !Convert.IsDBNull(o)) { i = (int)o; }

NAGARAJU TAMADA · Answer

Thans For The Answer Sir Here the Problem I found that there is no data in Database in beging of Execution .Thats Why The Exception raised.(System.InvalidCastException: Object cannot be cast from DBNull to other types.) Please Solve my Problem. Regards Nagaraju T

Iftikar Hussain · Answer

This query should work fine SELECT MAX(OrderNo) as LastOrderNo FROM PurchaseVendor Please share your table design Regards Iftikar

NAGARAJU TAMADA · Answer

try { string query = SELECT Count(OrderNo) as LastOrderNo FROM PurchaseVendor; DateTime currentDate = DateTime.Parse(dateString); int year = currentDate.Year; string branchName = comboSite.Text; SqlDataReader sqlDataReader = vendor.DataSourceClass.getSqlDataReader(query); while (sqlDataReader.Read()) { int i = Convert.ToInt32(sqlDataReader[LastOrderNo]); int j = 1; if (i > 0) { j = i + 1; txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } else { txtOrderNo.Text = QIEPL + / + year + / + branchName + / + PO + / + String.Format({0:00000} j); } } } In this code above sql query i need max(orderno) but not count(orderno) If i use max() itcauses some problems.I tried a lot but i didn't solve these problems . Regards NagaRaju T

Iftikar Hussain · Answer

You sql query is not returning any result. Please share your query. Regards Iftikar

Sanjeeb Lenka · Answer

hi paste your sql query what you are passing to database

NAGARAJU TAMADA · Answer

It causes The Exception like System.InvalidCastException: Object cannot be cast from DBNull to other types.

Sanjeeb Lenka · Answer

hi paste your query what it returns.

Iftikar Hussain · Answer

Hi I think your ExecuteScalar() is returning the integer value. If you are sure that it will always return integer datatype then please check your query directly in your sql first. to debbug the value what is it is returning you can check like this sqlConnection.Open(); SqlCommand command = new SqlCommand(query sqlConnection); object data = command.ExecuteScalar(); if(data!=null) { int i=Convert.ToInt32(data); } sqlConnection.Close(); Regards Iftikar

Vulpes · Answer

It's not clear from the code what type of field the query is returning but this should work regardless: string s = command.ExecuteScalar().ToString(); int i; bool isInt = int.TryParse(s out i); if (!isInt) { MessageBox.Show(Not an integer); }