SqlDataReader Datatype Conversion Error

Question

I am trying to load items from database in combobox but in code this unexpected error came and there seems to be no apparent reason. Please help. Error: Argument 1: Cannot convert from 'string' to 'int'. In database, the datatype of 'PortName' is Varchar.

Database Table

void FillCombo()
    {
        SqlConnection conn = new SqlConnection(global::flight_management.Properties.Settings.Default.conn);
        string sql = "SELECT PortName FROM PORTS";
        SqlCommand exesql = new SqlCommand(sql, conn);
        SqlDataReader myReader;
       try
        {
            conn.Open();
            myReader = exesql.ExecuteReader();
            while(myReader.Read())
            {
                string sName = myReader.GetString("PortName");
  // ERORR HERE: Argument 1: Cannot convert from 'string' to 'int'
                ComboFromA.Items.Add("sName");
            }
        }

        catch (Exception ex) {lblError.Text = "Error Loading Airports: "+ ex.Message;}
        finally {conn.Close();}
    }

Argument 1: Cannot convert from 'string' to 'int'

I've noticed from your code there appears to have a distinct mix of responsibilities in it. It is not best practice to have data access in a method which also is creating the items in a combobox for the UI. It maybe just pure example code, but still, something to think about :-) — WestDiscGolf
– WestDiscGolf, Commented Sep 17, 2017 at 13:50

Hüseyin Burak Karadag · Accepted Answer · 2017-09-17 13:50:58Z

2

Database types are important when reading data from SqlDataReader

ColumnType is String GetString

ColumnType is int GetInt32

ColumnType is Double GetDouble

you can use the one as the example I think this is the Best practice read value from SqlDataReader

myReader.GetString(myReader.GetOrdinal("PortName"));

And replace

ComboFromA.Items.Add("sName") to ComboFromA.Items.Add(sName);

edited Sep 17, 2017 at 13:50

answered Sep 17, 2017 at 13:44

Hüseyin Burak Karadag

1,88817 silver badges23 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Zain Ul Abidin · Accepted Answer · 2017-09-17 13:53:36Z

try the following code

void FillCombo()
    {
        SqlConnection conn = new SqlConnection(global::flight_management.Properties.Settings.Default.conn);
        string sql = "SELECT PortName FROM PORTS";
        SqlCommand exesql = new SqlCommand(sql, conn);
        SqlDataReader myReader;
       try
        {
            conn.Open();
            myReader = exesql.ExecuteReader();
            while(myReader.Read())
            {
                string sName = myReader.GetString(0);
  //ust use the index 0 for first attribute in select list 
                ComboFromA.Items.Add("sName");
            }
        }

        catch (Exception ex) {lblError.Text = "Error Loading Airports: "+ ex.Message;}
        finally {conn.Close();}
    }

Collectives™ on Stack Overflow

SqlDataReader Datatype Conversion Error

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related