Converting SQL int to C# string

Question

I've been trying to load an INT from my SQL-Server DB into my C# application and convert it into string.

Basically, it's the ID/Primary key of the DB Table that I want to use as string. This is what I do :

string Variable_ID;
Variable_ID = HandleDBNull(reader, "ID");

and I get a IndexOutOfRange exception.

Here is the HandleDBNullfunction :

    private string HandleDBNull(SqlDataReader r, string columnName)
    {
        if (!r.IsDBNull(r.GetOrdinal(columnName)))
            return r[columnName].ToString();
        else 
            return String.Empty;
    }

It works for the string columns so there seems to be something wrong with the conversion. I've already tried Convert.ToString and got the same error.

Any ideas?

isDBNull is a bad method-name. It suggests that it returns a bool. — Tim Schmelter
– Tim Schmelter, Commented Oct 4, 2012 at 9:37

Marc Gravell · Accepted Answer · 2012-10-04 09:38:08Z

3

I would guess that your columnName and columnOrder are out of step with each-other. One is wrong. Since they express the same information, one is redundant. I would use instead:

// probably should be renamed, btw
private string isDBNull(SqlDataReader r, int columnOrder)
{
    if (!r.IsDBNull(columnOrder))
    {
        return r[columnOrder].ToString();
    }
    else return "";
}

obviously with:

Variable_ID = isDBNull(reader, 0);

although I'm not quite sure I'd want everything as strings.

answered Oct 4, 2012 at 9:38

Marc Gravell

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2 Comments

hermann Over a year ago

Please check my edited code. I do not understand why your example works but what I'm trying to do doesn't.

Marc Gravell Over a year ago

@hermann sounds to me like the column name is not what you think it is. Look at r.GetName(0)

Aghilas Yakoub · Accepted Answer · 2012-10-04 09:36:35Z

2

You can try with - Because your condition is based on columnOrder

 ... 
 return r[columnOrder].ToString();

Suggestion

private bool isDBNull(SqlDataReader r, string columnName, int columnOrder)
    {
        if (!r.IsDBNull(columnOrder))
        {
            return true;
        }
        return false;
    }

answered Oct 4, 2012 at 9:36

Aghilas Yakoub

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Comments

Furqan Safdar · Accepted Answer · 2012-10-04 09:38:30Z

1

Simplify the code:

string Variable_ID;
Variable_ID = isDBNull(reader, "ID");

private string isDBNull(SqlDataReader r, string columnName)
{
    if (!r.IsDBNull(r.GetOrdinal(columnName)))
        return r[columnName].ToString();
    else 
        return string.Empty;
}

answered Oct 4, 2012 at 9:38

Furqan Safdar

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3 Comments

hermann Over a year ago

Thanks, one less parameter now. Original problem persists though.

Furqan Safdar Over a year ago

Same content replaced in question but no UpVote :(

Furqan Safdar Over a year ago

On which line or function are you getting the exception exactly.

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