If you are new in AX development or wants to do quick development by utilizing all intenseness feature given by Dynamics AX, you can achieve it with short hand written and a TAB key. For example if you want to find/use FOR LOOP in Dynamics AX, you can just type "for" (without quotes) and press Tab button, you will see full FOR loop syntax like below:
similiarly if you want to find the syntax of "while select" query, you can do it by typing "whileSelect" (without quotes, and a capital S this is case sensitive) and press Tab key/button, it will display you full "while select" statement like below:
Happy DAXing !!!!