I'm learning jdb, and have run into a weird issue: when I run a query
with a where clause requiring the equivalence of two columns, I get
an empty result, even though it should be nonempty. For example,
Reads__d 'winner,team from teammatch'
┌──────┬────┐
│winner│team│
├──────┼────┤
│SYD │CAR │
│SYD │SYD │
│ESS │ESS │
│ESS │FIT │
└──────┴────┘
Reads__d 'winner,team from teammatch where winner=team'
┌──────┬────┐
│winner│team│
├──────┼────┤
└──────┴────┘
Both fields are type 'char', and are from separate tables. I've pasted
some sample code below. Does anyone see the problem?
thanks,
Ryan
----------------------------------------
NB. requires that folder 'dbs' exists
require'data/jdb csv'
boxcsv=.([: <;._1 ','&,);._2
dataFromCsv=:<"_1@:|:@:}. NB. strip header and box columns
fixCol=: >each@{`[`]} NB. make unboxed column
fixNumCol=: ".@>each@{`[`]} NB. make unboxed numeric column
NB. match info, one row per match
CSV_matches=: boxcsv (0 : 0)
matchid,date,attendance,venue,winner,won_by,extra_time
1990-01-00,Sat 31-Mar-1990 2:10 PM,22427,Princes Park,SYD,5,0
1990-01-01,Sat 31-Mar-1990 2:10 PM,18960,Windy Hill,ESS,81,0
)
NB. match info per team, 2 rows per match
CSV_teammatches=: boxcsv (0 : 0)
matchid,team,score_progression,score
1990-01-00,CAR,6.5 10.9 12.15 14.15,99
1990-01-00,SYD,2.1 3.6 9.9 15.14,104
1990-01-01,ESS,7.4 13.11 17.15 20.21,141
1990-01-01,FIT,3.1 5.5 6.8 8.12,60
)
MatchData=: 4 fixCol 2 5 6 fixNumCol dataFromCsv CSV_matches
TeamMatchData=: 1 fixCol 3 fixNumCol dataFromCsv CSV_teammatches
MatchCols=: 0 : 0
matchid varchar;
date varchar
att int
venue varchar
winner char
wonby int
extratime boolean
)
TeamMatchCols=: 0 : 0
matchid match
team char
score_progression varchar
score int
)
f=: Open_jdb_ 'dbs'
Drop__f 'afltest'
d=: Create__f 'afltest'
Create__d'match';MatchCols; <MatchData
Create__d'teammatch';TeamMatchCols; <TeamMatchData
smoutput Reads__d '** from teammatch'
smoutput Reads__d '** from teammatch where winner=team' NB. Empty!
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