Scofield Reference Notes (1917 Edition)Chapter 22
22:1 And the inhabitants of Jerusalem made Ahaziah his youngest son king in his stead: for the band of men that came with the Arabians to the camp had slain all the eldest. So Ahaziah the son of Jehoram king of Judah reigned.
where he is called Jehoahaz. 2 Chronicles 21:17.