What should I use to compare DBNull ? Using DBNull.Value or ToString().IsNullOrEmpty()

Question

I can check for a DBnull on a data row using any of the methods.

Either by using

if(dr[0][0]==DBNull.Value)
//do somethin

or by doing

if(dr[0][0].ToString().IsNullOrEmpty())
//do something

In Both Cases I will be getting same result.

But Which one is conecptually right approach. Which was will use less resources

.ToString().IsNullOrEmpty()? Does a data row have 2 indices, dr[0][0]? And what if dr[0][0] is null, you can't call .ToString(). It is usually best to provide working code to get better answers. — Kobi
– Kobi, Commented Aug 3, 2010 at 6:10
@Kobi: My mistake you are right I meant to say DataTable if taking two indexers — Shantanu Gupta
– Shantanu Gupta, Commented Aug 3, 2010 at 6:15
for the second case, if the value in that column is null you'll be getting an error — devnull
– devnull, Commented Aug 3, 2010 at 6:21

Fyodor Soikin · Accepted Answer · 2010-08-03 06:10:01Z

28

The first way is somewhat correct. However, more accepted way is:

if ( dr[0][0] is DBNull )

And the second way is definitely incorrect. If you use the second way, you will get true in two cases:

Your value is DBNull
Your value is an empty string

answered Aug 3, 2010 at 6:10

Fyodor Soikin

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Comments

Rob · Accepted Answer · 2010-08-03 06:29:00Z

10

Conceptually the comparison to DBNull.Value is the correct one.

You can also use :

if (Convert.IsDBNull(dr[0]))
{
}

You could also use, which I'm not a fan of, purely because it's a type comparison rather than a value comparison:

if (dr[0] is DBNull)
{
}

edited Aug 3, 2010 at 6:29

answered Aug 3, 2010 at 6:10

Rob

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Comments

Julian de Wit · Accepted Answer · 2010-08-04 10:07:58Z

1

Is always use :

dr[0].IsNull(0)

Assuming that the creators of this function know the best way/most efficient way of comparing..

answered Aug 4, 2010 at 10:07

Julian de Wit

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Dragomok · Accepted Answer · 2017-01-05 19:09:59Z

0

The simplest way

if (dr[0][0] == DBNull.Value)
//do somethin

is perfectly valid and readable.

Even though == compares references, it works here because DBNUll.Value is the only instance of DBNull class - so all DBNull values are actually this exact reference.

answered Jan 5, 2017 at 19:09

Dragomok

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