Sorry, but you said it again. You imply that NULL is not meaningful. It is, and it has a very specific meaning in three state logic. If you use three state logic and it is not appropriate, it is a design issue. If you convert a NULL to another value, you have just destroyed the meaning of that value. For instance, if you change NULLs to a zero, aren't you now overloading the zero value to serve two different states - one where the value is unknown and one where the value is zero. Most BI tools DO know how to mange NULLs. For instance, if you are computing an average for a column, and the value for that column is NULL, it should be not be included in the average calculation. If the value is zero, it should be. This will have a very material effect on the computed answer.