how to check if a datareader is null or empty

user_84520 0
Viewed 213516

I have a datareader that return a lsit of records from a sql server database. I have a field in the database called "Additional". This field is 50% of the time empty or null.

I am trying to write code that checks if this field isnull. The logic behind this is: If the field "Additional" contains text then display the info otherwise hide the field.

I have tried:

if (myReader["Additional"] != null)
{
    ltlAdditional.Text = "contains data";
}
else
{
     ltlAdditional.Text = "is null";
}

The above code gives me this error:

Exception Details: System.IndexOutOfRangeException: Additional

Any help would be greatly appreciated...

See Also:

Check for column name in a SqlDataReader object

sqldatareader null c#
12 Answers
if (myReader["Additional"] != DBNull.Value)
{
    ltlAdditional.Text = "contains data";
}
else
{
     ltlAdditional.Text = "is null";
}
user_31320

First of all, you probably want to check for a DBNull not a regular Null.

Or you could look at the IsDBNull method

user_204710

In addition to the suggestions given, you can do this directly from your query like this -

SELECT ISNULL([Additional], -1) AS [Additional]

This way you can write the condition to check whether the field value is < 0 or >= 0.

user_836640

Try this simpler equivalent syntax:

ltlAdditional.Text = (myReader["Additional"] == DBNull.Value) ? "is null" : "contains data";
user_42952340

This

Example:

objCar.StrDescription = (objSqlDataReader["fieldDescription"].GetType() != typeof(DBNull)) ? (String)objSqlDataReader["fieldDescription"] : "";
user_93052650

AMG - Sorry all, was having a blond moment. The field "Additional" was added to the database after I had initially designed the database.

I updated all my code to use this new field, however I forgot to update the actual datareader code that was making the call to select the database fields, therefore it wasn't calling "Additional"

user_845200
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