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#!/usr/bin/env perl
# vim:set ts=4 sw=4 sts=4 et ai wm=0 nu:
#=============================================================================
# Copyright (c) 2024, Bob Lied
#=============================================================================
# PWC 263 Task 2 Alternative using SQLite
#=============================================================================
use v5.38;
use DBI;
use DBD::SQLite;
sub createDB()
{
my $dbh = DBI->connect("dbi:SQLite:dbname=:memory:", "", "",
{ PrintError => 1, PrintWarn => 1, RaiseError=>1});
# $dbh->trace($dbh->parse_trace_flags('SQL|1|test'));
return $dbh;
}
sub createTbl($dbh, $name)
{
my $ddl = <<"_CREATE_TBL_";
CREATE TABLE $name (
item INT(11) NOT NULL,
count INT(11) NOT NULL
);
_CREATE_TBL_
$dbh->do($ddl);
}
sub insert($dbh, $tbl, @lists)
{
my $sql = <<"_SQL_";
INSERT INTO $tbl(item, count) VALUES (?,?);
_SQL_
my $stmt = $dbh->prepare($sql);
for my $list ( @lists)
{
for my $pair ( $list->@* )
{
$stmt->execute( $pair->[0], $pair->[1] );
}
}
$stmt->finish();
}
sub dumpTbl($dbh, $tbl)
{
my $sql = "SELECT * FROM $tbl;";
my $stmt = $dbh->prepare($sql);
$stmt->execute();
while (my @row = $stmt->fetchrow_array)
{
say "$row[0], $row[1]";
}
}
sub mergeItems($dbh, $tbl)
{
my $sql = <<"_SQL_";
SELECT item, SUM(count)
FROM inventory
GROUP BY item;
_SQL_
my $stmt = $dbh->prepare($sql);
$stmt->execute();
my $result = $stmt->fetchall_arrayref;
$stmt->finish();
return $result;
}
use constant TBL => "inventory";
my $items1 = [ [1,1], [2,1], [3, 2] ];
my $items2 = [ [2,2], [1,3] ];
my $dbh = createDB();
createTbl($dbh, TBL);
insert($dbh, TBL, $items1, $items2);
# dumpTbl($dbh, TBL);
my $total = mergeItems($dbh, TBL);
for my $pair ( $total->@* )
{
say "SUM: $pair->[0], $pair->[1]";
}
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