dbnull

I had this interesting discussion today with a colleague. We were debating two pieces of code in C#. Code Snippet 1: if(!reader.IsDBNull(2)) { long? variable1 = reader.GetInt64(2) } Code Snippet 2: long variable1 = reader.IsDBNull(2) ? (long?) null : reader.GetInt64(2) Question is: is it a good practice to cast null into a nullable long? Or would you rather use the traditional if statement to avoid casting null to nullable long. The expressions (type?)null , default(type?) and new Nullable<type>() end up being compiled into the same opcodes: long? x = (long?)null; long? y = default(long?);

I have the following line of code if (DBNull.Value.Equals(o) || o != null) where o is object o in row.ItemArray I keep getting an error of --> Xml type "List of xdt:untypedAtomic" does not support a conversion from Clr type "DBNull" to Clr type "String". What I don't understand is that when I step through my code this if should be catching this and performing my alternate action but it does not? Can someone please shed some light for me. Thank you! Try using Convert.IsDBNull method. I think you problem is that in fact DBNull.Value == null //is always false The DBNull is a special class for

I am using a dataset to pull data from a DB. One of the fields in a row is NULL . I know this. However, the following vb.net code throws a StrongTypingException (in the autogenerated get_SomeField() method in the dataset designer): If Not IsDBNull(aRow.SomeField) Then 'do something End If According to documentation and this question it should be fine. edit: If aRow.SomeField is DBNull.Value Then also returns the same error. Argh. The difference is that in the related question it is talking about an untyped value (i.e. object ) via an indexer. When you go via .SomeField , the type is already

I have two DateTime objects, BirthDate and HireDate. They are correctly formatted as a string and when I pass them through to my data access layer, they need to be parsed into a DateTime object. DateTime hD = DateTime.Parse(hire); DateTime bD = DateTime.Parse(birth); //incase of a datestring being passed through dateStringPassed = "7/2/1969"; But sometimes, the strings hire and birth are null or empty "" , if the code is run like this, I get a FormatException error from Parsing a empty string. How can I manage empty parses and allow the DateTime, if empty or null, be accepted as DBNull.Value ?

(LocalVariable)ABC.string(Name)= (Idatareader)datareader.GetString(0); this name value is coming from database.. what happening here is if this name value is null while reading it's throwing an exception? I am manually doing some if condition here. I don't want to write a manual condition to check all my variables.. I am doing something like this now.. string abc = (Idatareader)datareader.GetValue(0); if(abc = null) //assiging null else assiging abc value is there something like can we write extension method for this? thanks Here is a couple extension methods that will nicely wrap up all of

I have the following C# code: sqlCommand.Parameters.AddWithValue("@Parameter", table.Value ?? DBNull.Value); But it throws the following compilation error: Operator ?? cannot be applied to operands of type string and System.DBNull Why doesn't the compiler allow this syntax? Pavel Urbančík Both operands need to be object. Use explicit cast: (object)table.Value ?? DBNull.Value; There is no automatic conversion between string and System.DBNull and so you need to specify the type you want explicitly by adding a cast to object : sqlCommandObject.Parameters.AddWithValue("@Parameter", table.Value ??