How to combine multiple columns into one column in kdb?

Question

I have written a below code that works, but I think there would be a better way to solve this problem.

I have something like this

table:([]time:9 11;Bid1px:4 5;Bid2px:7 3;Bid3px:6 8);
time Bid1px Bid2px Bid3px
-------------------------
9    4      7      6
11   5      3      8
table:update All_bid:flip(Bid1px;Bid2px;Bid3px) from table;
time Bid1px Bid2px Bid3px All_bid
---------------------------------
9    4      7      6      4 7 6
11   5      3      8      5 3 8

I would like to write a code using Bidcols like the below but can't seem to find a way, any help would be appreciated.

Bidcols:`Bid1px`Bid2px`Bid3px;
table:update All_bid:flip(Bidcols????) from table;

Answer 1

One way would be to use # (take) which on tables will return a subset of columns. As a table in kdb is simply a list of dicts, can then use value each on this table to get the values for each row:

q)table:([]time:9 11;Bid1px:4 5;Bid2px:7 3;Bid3px:6 8)
q)Bidcols:`Bid1px`Bid2px`Bid3px;
q)// using just #, all_bid column is a table so each row is a dict
q)update all_bid:Bidcols#table from table
time Bid1px Bid2px Bid3px all_bid
-----------------------------------------------------
9    4      7      6      `Bid1px`Bid2px`Bid3px!4 7 6
11   5      3      8      `Bid1px`Bid2px`Bid3px!5 3 8
q)// adding value each gives us the final desired result
q)update all_bid:value each Bidcols#table from table
time Bid1px Bid2px Bid3px all_bid
---------------------------------
9    4      7      6      4 7 6
11   5      3      8      5 3 8