C# winform I need to verify data in a textbox is in the database table or blank.

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I have a C# Winform where I have a textbox I need to verify if the text entered is either in the database table or the textbox is blank. I am using a leave event.

I can verify the entered text in the textbox is in the table.

I can verify if the textbox is empty.

how can I do both?

What I have tried:

code to verify textbox entry is in the database table.

private void BillBCOValue_Leave(object sender, EventArgs e)
   {
      var testresult = GlobalConfig.AccountTable.GetByAccount(BillBCOValue.Text);

      if (testresult == null) 
            
      {
       MessageBox.Show("BCO must be a valid Account Code");
       BillBCOValue.Focus();
      }

Posted 17-Sep-20 16:20pm

MIDCOPC

Updated 17-Sep-20 18:27pm

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Sandeep Mewara · Accepted Answer · 2020-09-17T18:27:00

If I understood correct, wouldn't that be a simple if:

C#

private void BillBCOValue_Leave(object sender, EventArgs e)
{
  if(string.IsNullOrWhiteSpace(BillBCOValue.Text))
  {
     MessageBox.Show("Textbox empty!");
  }
  else
  {
      var testresult = GlobalConfig.AccountTable.GetByAccount(BillBCOValue.Text);
    
      if (testresult == null) 
            
      {
         MessageBox.Show("BCO must be a valid Account Code");
         BillBCOValue.Focus();
      }
  } 
}

Refer: String.IsNullOrWhiteSpace(String) Method (System) | Microsoft Docs[^]