Compare two compound columns in two tables

Question

I have two tables(see below) with sym and lp. I want to pull out every row from tab1 that doesn't have the complete set of symbols corresponding to the same sym from tab2.

tab1:([]sym:`EUR`AUD`GBP;lp:(`aa`bb`cc;`dd`ee;`ff`gg`aa`ee))
tab2:([]sym:`EUR`AUD`GBP;lp:(`aa`bb`ff`cc;`ee`dd;`gg`ff`ee`aa`rr`xx))

i.e. my result should be:

tab3:([]sym:`EUR`GBP;lp:(`ff;`rr`xx))

Thanks

Answer 1

I think this might fit what you're looking for:

q)b: where 0 <> count each a: (exec lp from tab2) except' (exec lp from tab1)
q)update lp: a b from tab1 b
sym lp
----------
EUR ,`ff
GBP `rr`xx

One assumption that I've made is that you always have the syms in the same order in both tables, is this always true?