Question

two conditions when by-election are held​

Answer 1

Explanation:

A by-election, also spelled bye-election, and also known as a special election (United States, the Philippines) or a bypoll (India), is an election used to fill an office that has become vacant between general elections.

In most cases these elections occur after the incumbent dies or resigns, but they also occur when the incumbent becomes ineligible to continue in office (because of a recall, ennoblement, criminal conviction, or failure to maintain a minimum attendance). Less commonly, these elections have been called when a constituency election is invalidated by voting irregularities.

Answer 2

1) if he/she resigns
2) if he/she dies

Hope it helps.