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abs() vs abs[] for fby “while” all() vs all[]
May I ask how does abs() differs from abs[] in a select statement using fby clause?
q)tab:([] sym:`g1`g3`g1`g1`g2`g3;price:-2.5 2 -0.5 -0.2 3 4) q)tab sym price --------- g1 -2.5 g3 2 g1 -0.5 g1 -0.2 g2 3 g3 4 q)select from tab where abs(price)=({abs max x};price) fby sym 'type [0] select from tab where abs(price)=({abs max x};price) fby sym ^ q)and also similarly, in my qsql, if I use all with square brackets, it throws a rank error but all() works fine
select from xxx where all[col=`a;col2=`b] //rank error
How do I know wher
Thank you! -
1 Reply
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<div>See these sections of docs on:</div>
Order of evaluation also matters: Left-of-Right Evaluation
abs(price)=({abs max x};price)Will run in order:
- ({abs max x};price)
- (price)=({abs max x};price)
- abs(price)=({abs max x};price)
whereas:
abs[price]=({abs max x};price)Will run in order:
- ({abs max x};price)
- abs[price]
- abs[price]=({abs max x};price)
This tries to pass 2 arguments to all which only takes one argument so you get a rank error
https://code.kx.com/q/ref/all-any/#all
all[col=a;col2=b]
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