Styjun

This is the error I get :

Additional information: An object or column name is missing or empty. For SELECT INTO statements, verify each column has a name. For other statements, look for empty alias names. Aliases defined as "" or [] are not allowed. Change the alias to a valid name.

when running this code; it is supposed to load data from SQL Server to Winforms

private void click(int y)

 Edit();
 clear_invo();

 SqlConnection con = new SqlConnection(@"Data Source=ANSARI-PC;Initial Catalog=BMS;Integrated Security=True");

 string tname = "";

 if (str == "Pur")
 
 tname = "PurchaseT";
 
 else if (str == "GRO")
 
 tname = "Gro_Chln_T";
 
 else if (str == "Gri-Chln_T")
 
 tname = "GRI";
 
 else if (str == "Job")
 
 tname = "JobT";
 

 string sql1 = "select * from [" + tname + "]";

 SqlDataAdapter sda1 = new SqlDataAdapter(sql1, con);
 DataSet dsi = new DataSet();

 con.Open();
 sda1.Fill(dsi);

 int bene_id = -1;

 try
 
 idtxt.Text = dsi.Tables[0].Rows[y][0].ToString();
 bene_id = Convert.ToInt32(dsi.Tables[0].Rows[y][1]); 
 
 catch (Exception ex)
 
 if (!(idtxt.Text == null))
 
 MessageBox.Show(ex.Message);
 
 

 con.Close();

 load_bene(bene_id);

 string challan_id =str+"-"+ idtxt.Text;
 Load_item(challan_id); 

 No_Edit();

I would add a default "else" to the end of your if statement. If you hit that then you have your answer...You're not meeting the if statement conditions.

Also, consider swapping that if statement for a switch statement.

UPDATE #1

Here's your function re-written with a switch statement and throwing a custom exception. I've also taken the liberty of refactoring your DB code and also implemented string interpolation.

Just to clarify as per previous comments, the issue looks as though your IF...ELSE statement is insufficient. The value of "str" is equal to something other than "Pur", "GRO", "Gri-Chln-T" or "Job" and so when none of these are matched, your "tname" variable still has no value.

You then use this empty variable to construct your SELECT query which equates to "SELECT * FROM []".

As a side note, I would also recommend not returning * from a query unless you absolutely require every row in the table AND every column in that table.

public class TableIdentificationException : Exception



private void click(int y)

 Edit();
 clear_invo();

 var tname = string.Empty;

 switch (str)
 
 case "Pur":
 tname = "PurchaseT";
 break;
 case "GRO":
 tname = "Gro_Chln_T";
 break;
 case "Gri-Chln_T":
 tname = "GRI";
 break;
 case "Job":
 tname = "JobT";
 break;
 default:
 var ex = new TableIdentificationException();
 ex.Data.Add("LookupString", str);
 throw ex;
 

 var bene_id = -1;

 using (var con = new SqlConnection(@"Data Source=ANSARI-PC;Initial Catalog=BMS;Integrated Security=True"))
 
 var sql1 = $"select * from [tname]";

 using (var sda1 = new SqlDataAdapter(sql1, con))
 
 var dsi = new DataSet();

 sda1.Fill(dsi);

 try
 
 idtxt.Text = dsi.Tables[0].Rows[y][0].ToString();
 bene_id = Convert.ToInt32(dsi.Tables[0].Rows[y][1]);
 
 catch (Exception ex)
 
 if (idtxt.Text != null) MessageBox.Show(ex.Message);
 
 
 

 load_bene(bene_id);

 var challan_id = $"str-idtxt.Text";

 Load_item(challan_id);

 No_Edit();