kdb conditional update and select in one query

Question

I can do this:

x:([]v: 4 2; w: 10 100)
x: update z:`test from x where v = 4
x

But i'd really like to be able to do the conditional update and select all in one hit. something like

select v, w, (select `test from x where v = v) from z

Is this possible in kdb?

score 4 · Answer 1 · answered Oct 31 '17 at 18:42

4

You could try

update z:?[v=4;`test;`] from x

answered Oct 31 '17 at 18:42

emc211

score 3 · Answer 2 · answered Oct 31 '17 at 18:40

3

Is the vector conditional if what you're looking for?

q)select v,w,z:?[v=4;`test;`] from x
v w   z
----------
4 10  test
2 100

answered Oct 31 '17 at 18:40

jomahony

2 Answers2