When you use the comparison operators in SQL with the Where clause, you can remove the columns with null values. If you need the values with null too, then you need to use the appropriate
ISNull function as follows:
where IsNull(columnname, value) not like 'comparisonValue'
Replace
columnname with the correct column name and
value with something like
'comparisonValue' & 'extraText'.
The extraText is just to ensure that you don't end up fetching a record that exactly matches the replacement value.