C# DataTable ItemArray returns '{}' - how can I test for null value?

Question

I have a DataTable resultSet; - I'm trying to check fields for null, but get an '{}' (empty-set ?) object back. Searches involving "{}" aren't yielding any appropriate solutions.

This is the code that isn't working as expected when the "fk_id" field is null:

if (resultSet.Rows[0].ItemArray[resultSet.Columns.IndexOf("fk_id")] == null)
{
   //never reaches here
}

Note: using an int index instead of the Columns.IndexOf() isn't the issue.

Also does the "{}" have some other name in C#?

Matt Hamilton · Accepted Answer · 2009-04-01 23:01:27Z

19

To check a column for DBNull in a DataSet, you can use the IsNull method:

if (resultSet.Rows[0].IsNull("fk_id"))

Your comparison against null is probably failing because DataSets don't use null to represent a "database NULL" value - they use DBNull.Value. If you need your code to work the way you've presented it, try this:

if (resultSet.Rows[0].ItemArray[resultSet.Columns.IndexOf("fk_id")] == DBNull.Value)

answered Apr 1, 2009 at 23:01

Matt Hamilton

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4 Comments

Nick Josevski Over a year ago

Great thank you, completely forgot about "DBNull.Value" - it's been a while since I've manipulated data sets

Kimball Robinson Over a year ago

I wonder why they designed it this way instead of just using null?

Matt Hamilton Over a year ago

@k.rob Because there was no Nullable<T> in .NET 1.0, so there was no way to represent an Int32 value of "null".

Kimball Robinson Over a year ago

you can also use Convert.IsDBNull(value)

stealthyninja · Accepted Answer · 2011-05-17 10:36:55Z

-2

try
{
    if (DT.Rows[0][0] != null)
    {      
      //your code
    }    
}    
catch    
{    
    MessageBox.Show("AUTHANICATION FAILED.");    
}

edited May 17, 2011 at 10:36

stealthyninja

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answered May 16, 2011 at 22:45

Adei

1

Comments

Khalid Rafique · Accepted Answer · 2012-01-26 07:24:34Z

-2

Please use:

dataTable.Select("FieldName is NULL")

this will give you the DataRows with null values in FieldName column.

answered Jan 26, 2012 at 7:24

Khalid Rafique

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