What do you mean by "greater than
NULL"? In SQL
NULL has the lowest value than any other value, regardless of data type, so are you simply after values that have a non-
NULL value? If not, what counts as having a "lower" value of
NULL in your set up?
Also, I don't follow what you mean by a column having a value greater than
NULL. Tables are made up or rows and columns; a single column won't have a valu "greater than" something else, it'll be a specific value in a row in that column that will.
Sample data and expected results will likely help us understand what you're trying to describe here; I suspect some important information is being lost in translation.
Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.