I remember in q, we can assign a temporary variable during select and use it again in the same column, but seems it is not working.
For example,
select (total+5)%(total:a+b) from t
this should be same as
select (a+b+5)%(a+b) from t
What is wrong with the above?
9. Queries q-sql - Q for Mortals (kx.com)
“Unlike in SQL, columns in the Select phrase do not actually exist until the final result table is returned. Thus a computed column cannot be used in other column expressions.”
You’ll need two different select statements here, e.g.
select (total+5)%total from select total:a+b from t
You cannot do inline temporary variable creation as @eohara pointed out.
Instead you can use a lambda to avoid performing the calculation twice:
q)select {[a;b] (total+5)%(total:a+b)}[a;b] from t b -------- 2 1.714286 1.555556
Or you can think in vectors:
q)show t:flipab!flip 3 2#2 3 4 5 6 7 a b — 2 3 4 5 6 7 q)select (a+b+5)%(a+b) from t a -------- 2 1.555556 1.384615 q)(%) . 5 0+:sum tab 2 1.555556 1.384615
Breaking that down:
q)tab / two cols, returned as a 2-row matrix 2 4 6 3 5 7 q)sum tab / a + b 5 9 13 q)5 0+:sum tab / (a+b) with and without 5 added 10 14 18 5 9 13 q)(%) . 5 0+:sum tab / their ratios 2 1.555556 1.384615