dbnull

This question comes up occasionally, but I haven't seen a satisfactory answer. A typical pattern is (row is a DataRow ): if (row["value"] != DBNull.Value) { someObject.Member = row["value"]; } My first question is which is more efficient (I've flipped the condition): row["value"] == DBNull.Value; // Or row["value"] is DBNull; // Or row["value"].GetType() == typeof(DBNull) // Or... any suggestions? This indicates that .GetType() should be faster, but maybe the compiler knows a few tricks I don't? Second question, is it worth caching the value of row["value"] or does the compiler optimize the

In .NET there is the null reference, which is used everywhere to denote that an object reference is empty, and then there is the DBNull , which is used by database drivers (and few others) to denote... pretty much the same thing. Naturally, this creates a lot of confusion and conversion routines have to be churned out, etc. So why did the original .NET authors decide to make this? To me it makes no sense. Their documentation makes no sense either: The DBNull class represents a nonexistent value. In a database, for example, a column in a row of a table might not contain any data whatsoever.

The following code gives an error - "No implicit conversion from DBnull to int." SqlParameter[] parameters = new SqlParameter[1]; SqlParameter planIndexParameter = new SqlParameter("@AgeIndex", SqlDbType.Int); planIndexParameter.Value = (AgeItem.AgeIndex== null) ? DBNull.Value : AgeItem.AgeIndex; parameters[0] = planIndexParameter; Chris Taylor The problem is that the ?: operator cannot determine the return type because you are either returning an int value or a DBNull type value, which are not compatible. You can of course cast the instance of AgeIndex to be type object which would satisfy