Working with null values in memory.

Question

Int32, bool, float, etc. are all memory structs/value types, and the value of "null" is a pointer (a zero pointer precisely) therefore it isn't possible to assign null to an struct/value type. This in itself isn't an issue until you throw in a database. The values from the database can be null, what strategies when working with null values in memory from one of the value types? I'm using C# to build a system. Thanks in advance.