Combobox item when select displaying wrong record in textbox

Dharam Rai

Hello all genius: My problem is I got two tables tbl_session where I have 'SessionID' 'SessionName' and tbl_Class where I have 'ClassID' 'SessionID' 'ClassName' (SessionID [FK] of tbl_Class is link with Session_ID[PK] of tbl_Session ]. There are same 'ClassName' in tbl_Class whose SessionID and ClassID is different, Now my query is, if select ClassName from combobox then display ClassID in textbox. But the problem is I have same ClassName, So as per my query when I choose ClassName it shows the different ClassID, but I want to achieve the ClassID of the same ClassName that displays in my combobox.

Here is my code to fill combo_Class:

private void FillClass(int SessionID)

{

string str = "SELECT ClassId, ClassName FROM ClassMaster WHERE SessionID =@SessionID";

OleDbCommand cmd = new OleDbCommand(str, connection);

cmd.Parameters.AddWithValue("@SessionID", SessionID);

DataSet objDs = new DataSet();

OleDbDataAdapter dAdapter = new OleDbDataAdapter();

dAdapter.SelectCommand = cmd;

connection.Open();

dAdapter.Fill(objDs);

connection.Close();

if (objDs.Tables[0].Rows.Count > 0)

{

combo_Class.ValueMember = "ClassId";

combo_Class.DisplayMember = "ClassName";

combo_Class.DataSource = objDs.Tables[0];

}

//And here is the code to select class from combo_Class and display ClassID in textbox:

private void combo_Class_SelectedIndexChanged(object sender, EventArgs e)

{

try

{

connection.Open();

OleDbCommand command = new OleDbCommand();

command.Connection = connection;

string query = " select * from ClassMaster where ClassName= '" + combo_Class.Text + "' ";

command.CommandText = query;

OleDbDataReader reader = command.ExecuteReader();

while (reader.Read())

{

txt_ClassId.Text = reader["ClassId"].ToString();

}

connection.Close();

}

catch (Exception ex)

{

MessageBox.Show("Error " + ex);

}

// Please help me please...

14 Replies

Know the answer? Post it — somebody with the same question will find it here.

Pramod Gayakwad10y ago
when classid string DB then u will used
string query = " select * from ClassMaster where classid=" + Convert.ToInt32(combo_Class.SelectedValue);

or
string query1 = " select * from ClassMaster where classid='" + combo_Class.SelectedValue + "'";

If you find anything useful please accept my answer
Manas Mohapatra10y ago
It looks like ClassId is integer type, so use your query like below:

string query = " select * from ClassMaster where ClassId= " + combo_Class.SelectedValue;

Note: if it doesn't resolve your problem the provide its data type, exception you are getting and value getting from combo_Class
Dharam Rai10y ago
@ Pramod, I am trying your code but it is throwing error : "Data type mismatch in criteria expression"

private void combo_Class_SelectedValueChanged(object sender, EventArgs e)
{
try
{
connection.Open();
OleDbCommand command = new OleDbCommand();
command.Connection = connection;
string query = " select * from ClassMaster where ClassId= '" + combo_Class.SelectedValue + "' ";
//string query =" Select * from ClassMaster where ClassName = '"+combo_Class.Text+"'";
command.CommandText = query;
OleDbDataReader reader = command.ExecuteReader();
while (reader.Read())
{
txt_ClassId.Text = reader["ClassId"].ToString();
// txt_ClassId.Text = combo_Class.SelectedValue.ToString();

}
connection.Close();
}

catch (Exception ex)
{
MessageBox.Show("Error " + ex);
}
}

I am attaching the error screen shot, kindly look for it:
puneet ahooja10y ago
Dear Friend,

Try this query in MS Access firstly ( for Testing)

SELECT ClassMaster.ClassId,ClassMaster.ClassName,ClassMaster.SessionId FROM ClassMaster where ClassMaster.ClassId='5';

I am enclosing the database file for your reference.

Regards
Puneet

Pramod Gayakwad10y ago

ClassId	ClassName	SessionID
1	Class-7A	1
2	Class-8A	1
3	Class-8A	1
4	Class-7A	2
5	Class-8A	2
6	Class-9A	2
7	Class-7A	3
8	Class-8A	3

don't use class name for filteration use classid

like string query = " select * from ClassMaster where classid= '" + combo_Class.selectedvalue ;

Dharam Rai10y ago
@Dear Manas, I tried re downloading the database I attached from other PCs it is working fine, kindly download again and unzipped it. Thanks once again.
Manas Mohapatra10y ago
Sorry, I am not able to open it. So I ma asking if you can provide a demo example here it would be better.
Dharam Rai10y ago
@ Dear Manas kindly download the database I attached, then you'll be clear of my question. Thanks, but I am looking for a solution.
Manas Mohapatra10y ago
When you this kind of problem, please provide an example.

ClasssID ClassName SessionID
1 cls-9 4
1 cls-9 5
2 cls-6 1

Just define your requirement and what do you need exactly.
Dharam Rai10y ago
@Dear Puneet here I am attaching my database table, kindly check.
puneet ahooja10y ago
Dear Friend ,

Please share your database table fields.

As per your coding there is something missing between database table field and query.

Or

for your knowledge/ information , you can create a dummy table for testing the database in MS Access 2007 and run the query.

Awaitig for your reply!!!!

Regards
Puneet
puneet ahooja10y ago
Dear Friend,

Please share your database table fields.

As per your coding there is something missing between database table field and query.

Regards
Puneet
Dharam Rai10y ago
@ Dear Puneet I don't receive any error, the only thing is it displays the result of the wrong ClassID. My question is how to write a right query, I know my query is wrong :
string query = " select * from ClassMaster where ClassName= '" + combo_Class.Text + "' ";

My query is reading ClassName from combobox but it reads from the database, so the problem is I have duplicate name in the database, For example Class Name I have two similar Class Name such as Class-9A and Class-9A the only difference between this two is their ClassId and SessionID. Therefore when the query reads the ClassName from the combobox it reads and return the ClassID of the other duplicate ClassName but not the one which shows in the combobox.

Dear Puneet kindly help. :(
puneet ahooja10y ago
Dear friend,

What is the error message you received ?