In "Star Trek: T.N.G", how many captains did Enterprise "D" have?

Question

As in official command changes.

Answer 1

Captain Picard sat in the chair, but was captured by the Borg in The Best Of Both Worlds (Season Three/Four), with Riker taking the captaincy for the duration of the story.

Picard was later relieved of command by Admiral Nechayev in the Season Six two-parter, Chain Of Command, where Captain Jellico took command of the Enterprise.

So that'll be three times.

Answer 2

Three, if you count the episode when the Borg arrive in Federation space and whale the tar out of Starfleet, taking Picard prisoner. (There was that double-episode when Ronny Cox took the chair.)