C# – How to check for null values

cnetsubsonic

I have an integer column that may have a number or nothing assigned to it (i.e. null in the database). How can I check if it is null or not?

I have tried

if(data.ColumnName == null)
{
    ...
}

This doesn't work either (as SubSonic does not use nullable types (when applicable) for ActiveRecord)

if(data.ColumnName.HasValue)
{
    ...
}

If the value stored in the database is 0, then this wouldn't help:

if(data.ColumnName == 0 /* or 0x000? */)
{
    ...
}

The same problem could also occur with DateTime fields as well.

Best Answer

Try:

If (data == System.DBNull)

Related Solutions

C# – How to calculate someone’s age based on a DateTime type birthday

An easy to understand and simple solution.

// Save today's date.
var today = DateTime.Today;

// Calculate the age.
var age = today.Year - birthdate.Year;

// Go back to the year in which the person was born in case of a leap year
if (birthdate.Date > today.AddYears(-age)) age--;

However, this assumes you are looking for the western idea of the age and not using East Asian reckoning.

C# – How to cast int to enum

From an int:

YourEnum foo = (YourEnum)yourInt;

From a string:

YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourString);

// The foo.ToString().Contains(",") check is necessary for enumerations marked with an [Flags] attribute
if (!Enum.IsDefined(typeof(YourEnum), foo) && !foo.ToString().Contains(","))
{
    throw new InvalidOperationException($"{yourString} is not an underlying value of the YourEnum enumeration.")
}

Update:

From number you can also

YourEnum foo = (YourEnum)Enum.ToObject(typeof(YourEnum) , yourInt);

Best Answer

Related Solutions

C# – How to calculate someone’s age based on a DateTime type birthday

C# – How to cast int to enum

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