A NULL never equals '', so a condition written that way returned zero rows. The
question is perfectly clear — the operator wants the ones with nothing in that
field — and answering it with silence makes the filter look broken rather than
mis-stated. eq and ne with a blank value now run the empty / not-empty test.
Empty on a NUMERIC column also had a real fault behind it. IFNULL(col,'')=''
compares 0 against '', which SQLite calls false and MySQL calls true — one
expression quietly answering two different questions depending on where the
logbook lives. Numeric columns test NULL or zero explicitly now; text keeps the
string test, where '' is a real value and 0 is not.