Does this sentence need a semicolon

Jim isn't here now, and he hasn't been here all day

Yes

Explanation:

This sentence needs a semicolon where it has only a comma, because a semicolon means that the idea finishes, but the sentence doesn't, so it needs a semicolon because a full stop would mean a definitive closure for the idea that he isn't here, and it would mean excluding the rest of the sentence.