How to Display name using combobox id

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Anyone Please help

i have 2 form . in first form have two textbox id and name and one save button and second form have one combo and one textbox. i want, when form-2 loaded then database table id's fill in form -2 combobox and if i select any id in combobox then releted id name display in form 2 textbox.

i tried this...but one error is coming
ERROR->Conversion failed when converting the varchar value 'System.Data.DataRowView' to data type

 // FORM-1 CODE
 private void cmdsave_Click(object sender, EventArgs e)
        {
            conn = new SqlConnection(@"Data Source=MANISH-PC\SQLEXPRESS;Initial Catalog=test2.mdf;Integrated Security=True");
            conn.Open();
            SqlCommand command = new SqlCommand();
            command.CommandText = "insert into table1(name)values('" + textBox2.Text + "')";
            command.Connection = conn;
            command.ExecuteNonQuery();
            MessageBox.Show("successfully Saved");
         }
 
//FORM-2 CODE

 private void Form2_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the '_test2_mdfDataSet.Table1' table. You can move, or remove it, as needed.
            this.table1TableAdapter.Fill(this._test2_mdfDataSet.Table1);
             }
 
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            SqlConnection conn = new SqlConnection(@"Data Source=MANISH-PC\SQLEXPRESS;Initial Catalog=test2.mdf;Integrated Security=True");
            conn.Open();
            SqlCommand command = new SqlCommand("select name from table1 where id='"+comboBox1.SelectedItem+"'", conn);
            SqlDataAdapter adp = new SqlDataAdapter(command);
            tbl = new DataTable();
            adp.Fill(tbl);
            textBox1.Text = tbl.Rows[1].ToString();
}

Posted 31-Mar-14 9:09am

guru14

Updated 31-Mar-14 9:16am

Richard C Bishop

v2

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Comments

Richard C Bishop 31-Mar-14 15:18pm

Where does this fail at? Your insert statement will definitely fail, does it fail anywhere else?

guru14 31-Mar-14 15:26pm

my insert statement correct..actually id is auto generated
(identity increment=1)

ZurdoDev 31-Mar-14 16:53pm

1. Your insert statement is open to SQL injections which means someone could do whatever they wanted to with your database through this form. That may be what Richard was referring to.
2. Where is the error? And what is the complete error?

guru14 31-Mar-14 23:35pm

error coming here -adp.Fill(tbl); and it's a complete error -
Error type -> SqlException was Unhandled
Error -> Conversion failed when converting the varchar value 'System.Data.DataRowView' to data type

ZurdoDev 1-Apr-14 6:29am

That isn't the complete error. You can even see that it isn't a complete sentence. No matter, Solution 1 has the answer.

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Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) · Answer 1 · 2014-03-31T20:23:00

Solution 1

That is because you are assigning comboBox1.SelectedItem to id in query. That is actually a object, but you should be providing the value.

Use SelectedValue Property[^] to get the value.

C#

SqlCommand command = new SqlCommand("select name from table1 where id='" + comboBox1.SelectedValue +"'", conn);

But you should always use Parameterized query to avoid SQL Injection issues.

C#

SqlCommand command = new SqlCommand("select name from table1 where id=@id", conn);
command.Parameters.AddWithValue("@id", comboBox1.SelectedValue);

Posted 31-Mar-14 20:23pm

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ)

Comments

guru14 1-Apr-14 4:22am

Thanks for reply. I made changes in my code as per your suggestion and run program but one error is coming in adp.fill(tbl);
Error-No mapping exists from object type System.Data.DataRowView to a known managed provider native type.

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 1-Apr-14 4:35am

Okay, seems like the ComboBox is bound from a DataTable, so its type is System.Data.DataRowView. If you've neglected to set the ValueMember for one or more of those ComboBoxes the the SelectedValue will return the same as the SelectedItem, i.e. a DataRowView.

So now try like below...

SqlCommand command = new SqlCommand("select name from table1 where id=@id", conn);
command.Parameters.AddWithValue("@id", comboBox1.SelectedValue.ToString());

While debugging check what is the value of comboBox1.SelectedValue.ToString().

guru14 1-Apr-14 8:35am

if i used this command.Parameters.AddWithValue("@id", comboBox1.SelectedValue.ToString());
then Conversion failed when converting the varchar value 'System.Data.DataRowView' to data type int error coming if i not use Tostring(); inside of query then No mapping exists from object type System.Data.DataRowView to a known managed provider native type. coming
now what should i do sir ..

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 1-Apr-14 8:48am

As I said, did you check what is the value of comboBox1.SelectedValue.ToString() while debugging? Is the value correct?

guru14 1-Apr-14 8:56am

Value of combobox.selectedvalue.tostring is System.Data.DataView.

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 1-Apr-14 9:16am

That is the problem. We need to get the data from this.

Try like below...

string sval = ((DataRowView)comboBox1.SelectedValue).Row["ColumnName"].ToString();
command.Parameters.AddWithValue("@id", sval);

Replace correct Column Name here.

guru14 1-Apr-14 9:50am

Thanks once again for continues reply.
New Error->Fill: SelectCommand.Connection property has not been initialized.
updated code...
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{

SqlCommand command = new SqlCommand();
string sval = ((DataRowView)comboBox1.SelectedValue).Row["name"].ToString();
command.Parameters.AddWithValue("@id", sval);
SqlDataAdapter adp = new SqlDataAdapter(command);
command.connection=conn;
DataTable tbl = new DataTable();
adp.Fill(tbl);
textBox1.Text = comboBox1.SelectedValue.ToString();
}

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 1-Apr-14 10:22am

Try like below...

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
SqlCommand command = new SqlCommand();
string sval = ((DataRowView)comboBox1.SelectedValue).Row["name"].ToString();
command.Parameters.AddWithValue("@id", sval);
command.connection=conn;
SqlDataAdapter adp = new SqlDataAdapter(command);
DataTable tbl = new DataTable();
adp.Fill(tbl);
textBox1.Text = comboBox1.SelectedValue.ToString();
}