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SQL is the unnecessary complexity you don't want in such a simple task. Besides DBD::CSV implements a very limited subset of SQL.

What you should do is just to have a single pass over your file reading a line at the time, build your hash table of statistics along the way while splitting the records, and print out the stats at the end.

my %stats; open MYFILE, "<data.txt" or die "Can not open file: $!"; chomp(my $heading = <MYFILE>); my @col = split /,/, $heading; while (my $line = <MYFILE>) { # build a hash for the input record chomp($line); my @rec = split /,/, $line; my %rec; @rec{@col} = @rec; # collect stats $stats{$rec{rec_id}}{BAL} += $rec{bal}; $stats{$rec{rec_id}}{NUM} ++; } # print the stats here for my $id (keys %rec) { if ($rec{$id}{NUM}) { print "$id => ", $rec{$id}{BAL}/$rec{$id}{NUM}, "\n" } } close MYFILE;

In reply to Re^3: Advances SQL calculations in CSV file by Roger
in thread Advances SQL calculations in CSV file by DrAxeman

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