Hi, say I have a trade table with trade of multiple symbols, I would like to assign an auto-increment id per trades of individual symbols so that it is easier to compare with another trade table, but I am not sure how to do that, would you help to suggest?
Theres no built in way. Theres the i column in each table but it is dependent on order, deletions etc. You just have to do it yourself e.g.
q)ID:0
q)tab:(a:(); id:())
q)insertid:{[t;x] insert[t;update id:ID+til count x from x]; ID+::count x}
q)insertid[`tab;(a:8 9 10)]
q)tab
a id
8 0
9 1
10 2
q)insertid[`tab;(a:8 9 10)]
q)tab
a id
8 0
9 1
10 2
8 3
9 4
10 5
q)delete from `tab where a=9
`tab
q)insertid[`tab;(a:8 9 10)]
q)tab
a id
8 0
10 2
8 3
10 5
8 6
9 7
10 8
Thanks Jonny, I am not really understand how to apply the above logic to create auto-increment id, the trade table schema is something like this:
trade:(time:time$();sym:symbol$();price:float$();size:int$())
Say there are few rows for AAPL, and few rows for GOOG, how can I assign sequence numbers as auto-increment id to difference trades for difference symbols?
On Tue, Apr 26, 2016 at 9:24 PM, Jonny Press <pressjonny0@gmail.com> wrote:
Theres no built in way. Theres the i column in each table but it is dependent on order, deletions etc. You just have to do it yourself e.g.
q)ID:0
q)tab:(a:(); id:())
q)insertid:{[t;x] insert[t;update id:ID+til count x from x]; ID+::count x}
q)insertid[`tab;(a:8 9 10)]
q)tab
a id
8 0
9 1
10 2
q)insertid[`tab;(a:8 9 10)]
q)tab
a id
8 0
9 1
10 2
8 3
9 4
10 5
q)delete from `tab where a=9
`tab
q)insertid[`tab;(a:8 9 10)]
q)tab
a id
8 0
10 2
8 3
10 5
8 6
9 7
10 8
On 26 Apr 2016, at 12:03, Carfield Yim <carfield@gmail.com> wrote:
Hi, say I have a trade table with trade of multiple symbols, I would like to assign an auto-increment id per trades of individual symbols so that it is easier to compare with another trade table, but I am not sure how to do that, would you help to suggest?
–
Submitted via Google Groups
If you just want to treat it as a temporary ID then just use i e.g.
update id:i from `trade
If you want the id to reset per sym (Im not sure if that is what you are ask) then do it by sym e.g.
update id:til count i by sym from `trade
I see, thanks a lot