Mark

Fair enough about the staging table - it was just a suggestion. Might still be worth considering on the output table, though.

If I may say so, the thing about second meanings isn't the point. A NULL should represent an unknown value and nothing else. Take the example about names. If you have MiddleName is blank, that means that person doesn't have a middle name. If you have MiddleName is NULL, that means you don't know what that person's middle name is, or whether they have one. See the difference? If you turn all blanks into NULLs, you lose the ability to make that distinction.

John