How to Perform IF function when selecting Combobox item?

Question

How to Perform IF function when selecting Combobox item?

Asked 6 years, 8 months ago

Viewed 1,578 times

2

I wanted to know how to make one if function only when the combobox have any item selected. I am making a program in windows Forms and I need a if to limit the program to only do that function when the combobox contain something selected. This is the code I have to limit:

 if () {
    var adapter = new OleDbDataAdapter("SELECT * FROM [" + comboBox1.SelectedText + "$]", conexao);
    var ds = new DataSet();
    adapter.Fill(ds, comboBox1.SelectedText + "$");
    DataTable data = ds.Tables[comboBox1.SelectedText + "$"];

    foreach (DataColumn dc in data.Columns)
    {
         comboBox2.Items.Add(dc.ColumnName);
         comboBox3.Items.Add(dc.ColumnName);
         comboBox4.Items.Add(dc.ColumnName);
         comboBox5.Items.Add(dc.ColumnName);
    }
 }

I fill out the combobox1 with this code:

using (OpenFileDialog ofd = new OpenFileDialog() { Filter = "Excel Workbook|*.xls", ValidateNames = true })
            {
                if (ofd.ShowDialog() == DialogResult.OK)
                {
                    FileStream fs = File.Open(ofd.FileName, FileMode.Open, FileAccess.Read);
                    IExcelDataReader reader = ExcelReaderFactory.CreateBinaryReader(fs);
                    reader.IsFirstRowAsColumnNames = true;
                    result = reader.AsDataSet();
                    comboBox1.Items.Clear();

                    foreach (DataTable dt in result.Tables) comboBox1.Items.Add(dt.TableName);
                    reader.Close();

                    string ConecçãoDB = ConfigurationManager.ConnectionStrings["ConecçaoDB"].ConnectionString;
                    string Table = ConfigurationManager.AppSettings["table"];

                    string ssqltable = Table;

                    string ssqlconnectionstring = ConecçãoDB;

                    filename = ofd.FileName;
                     MessageBox.Show(Convert.ToString(filename));
                    var connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + filename + ";Extended Properties=\"Excel 12.0;IMEX=1;HDR=YES;TypeGuessRows=0;ImportMixedTypes=Text\"";

                    var conexao = new System.Data.OleDb.OleDbConnection(connectionString);

                    var sql = "SELECT * FROM [PARAC1$]";
                    string sclearsql = "delete from " + ssqltable;
}
}

Question too broad, vague is Web is Forms is in which of them? lack to give a contextualized and put more information .

– novic

2017/10/12 at 13:58
@Virgilionovic already updated my question , I apologize .

– Pedro Azevedo

2017/10/12 at 14:00
1

Put the current code! also this helps to clear more ...

– novic

2017/10/12 at 14:00
comboBox1.Selectedtext is named after spreadsheets?

– novic

2017/10/12 at 14:03
1

@Virgilionovic Yes ,has .

– Pedro Azevedo

2017/10/12 at 14:03

2 answers

3

if (comboBox1.Items.Count > 0) comboBox1.SelectedIndex = 0; // posiciona no primeiro item
if (string.IsNullOrEmpty(comboBox1.Text) == false) 
{
    var adapter = new OleDbDataAdapter("SELECT * FROM [" 
                         + comboBox1.Text+ "$]", conexao);
    var ds = new DataSet();
    adapter.Fill(ds, comboBox1.Text+ "$");
    DataTable data = ds.Tables[comboBox1.Text + "$"];

    foreach (DataColumn dc in data.Columns)
    {
        comboBox2.Items.Add(dc.ColumnName);
        comboBox3.Items.Add(dc.ColumnName);
        comboBox4.Items.Add(dc.ColumnName);
        comboBox5.Items.Add(dc.ColumnName);
    }
}

I do not know why but so does not write in the other combobox the names of the columns

– Pedro Azevedo

2017/10/12 at 14:11
If you have already debugged the code @Pedroazevedo ??? with breakpoint?

– novic

2017/10/12 at 14:12
Yes, it just doesn’t do anything

– Pedro Azevedo

2017/10/12 at 14:14
made an issue @Pedroazevedo is Text take a look!

– novic

2017/10/12 at 14:16
It does nothing I tried to put in the code a message box and it does not appear

– Pedro Azevedo

2017/10/12 at 14:20
How do you fill it @Pedroazevedo put in your question.

– novic

2017/10/12 at 14:22
How do I fill in what ?

– Pedro Azevedo

2017/10/12 at 14:23
How do you upload the information to comboBox1 ???

– novic

2017/10/12 at 14:24
I’ve already updated .

– Pedro Azevedo

2017/10/12 at 14:28
@Pedroazevedo you updated the way I did in the reply?

– novic

2017/10/12 at 14:29
Yeah, it still didn’t work

– Pedro Azevedo

2017/10/12 at 14:32
It must be a local problem of difficult reproduction, you know if it enters in this if() using breakpoint and F11 ???

– novic

2017/10/12 at 14:33
He passes the if, never gets in

– Pedro Azevedo

2017/10/12 at 14:35
Let’s go continue this discussion in chat.

– novic

2017/10/12 at 14:37

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by Agnaldo • **162** points · Answer 1 · 2017-10-12T14:58:38+00:00

You want to perform certain function when some item of your Combobox is selected right?

At the event Selectedindexchanged of Combobox it is possible to perform such action, see.

private void meuComboBox_SelectedIndexChanged(object sender, EventArgs e){
   if (meuComboBox.SelectedIndex >= 0)
      //Executa sua função "if" aqui
   }