So I’m practising kdb with some self-imposed challenges. This one is a program supposed to tell you if it’s someone’s birthday today. (I just used letters instead of names in this version).

My question is this: what are those three nulls that the terminal outputs?

.aaa.bdic: `a`b`c!((01 12);(02 01);(29 04))

.aaa.bdic
a| 1  12
b| 2  1 
c| 29 4 

  {if[((`dd $ .z.P)=.aaa.bdic[x][0]) and (`mm $ .z.P)=.aaa.bdic[x][1]; show "it's " , (string x) , "'s birthday!"]}each key .aaa.bdic

"it's c's birthday!"
::
::
::

I tried adding another item to my dictionary and I got four nulls instead of three.