Question

I’ve got a DateTime? that I’m trying to insert into a field using a DbParameter. I’m creating the parameter like so:

DbParameter datePrm = updateStmt.CreateParameter(); datePrm.ParameterName = '@change_date'; 

And then I want to put the value of the DateTime? into the dataPrm.Value while accounting for nulls.

I thought initially I’d be clever:

datePrm.Value = nullableDate ?? DBNull.Value; 

but that fails with the error

Operator ‘??’ cannot be applied to operands of type ‘System.DateTime?’ and ‘System.DBNull’

So I guess that only works if the second argument is a non-nullable version of the first argument. So then I went for:

datePrm.Value = nullableDate.HasValue ? nullableDate.Value : DBNull.Value; 

but that doesn’t work either:

Type of conditional expression cannot be determined because there is no implicit conversion between ‘System.DateTime’ and ‘System.DBNull’

But I don’t want to convert between those types!

So far the only thing I can get to work is:

if (nullableDate.HasValue)   datePrm.Value = nullableDate.Value; else   datePrm.Value = DBNull.Value; 

Is that really the only way I can write this? Is there a way to get a one-liner using the ternary operator to work?

Update: I don’t really get why the ?? version doesn’t work. MSDN says:

The ?? operator returns the left-hand operand if it is not null, or else it returns the right operand.

That’s exactly what I want!

Update2: Well it was kind of obvious in the end:

datePrm.Value = nullableDate ?? (object)DBNull.Value; 

Answer 1

Ah ha! I found an even more efficient solution than @Trebz’s!

datePrm.Value = nullableDate ?? (object)DBNull.Value;