循环遍历perl中的散列

Question

现在我正在学习perl，并且有一个简短的脚本，在这个脚本中，我访问一个数据库(DBI模块)以提取一些统计数据。下面的代码看起来有点重复，我想知道它是否可以简化为一个哈希循环。每个数据库查询的唯一区别是myo_maps_study中的正则表达式

#Get the number of myo stress studies
$sth = $dbh->prepare("SELECT count(myo_maps_study) FROM myo WHERE myo_maps_study ~ 'MYO[0-9]*\$' AND myo_date <= ? AND myo_date >= ?");
$sth->execute($date_stop,$date_start) or die "Couldn't execute myo stress query" . $sth->errstr;
my $n_myo_stress = $sth->fetchrow_array;

#Get the number of myo redistribution studies
$sth = $dbh->prepare("SELECT count(myo_maps_study) FROM myo WHERE myo_maps_study ~ 'MYO[0-9]*R\$' AND myo_date <= ? AND myo_date >= ?");
$sth->execute($date_stop,$date_start) or die "Couldn't execute myo rep query" . $sth->errstr;
my $n_myo_rep = $sth->fetchrow_array;

#Stress tomos
$sth = $dbh->prepare("SELECT count(myo_maps_study) FROM myo WHERE myo_maps_study ~ 'MYO[0-9]*T\$' AND myo_date <= ? AND myo_date >= ?");
$sth->execute($date_stop,$date_start) or die "Couldn't execute myo stress tomo query" . $sth->errstr;
my $n_stress_tomo = $sth->fetchrow_array;

#Rest tomos
$sth = $dbh->prepare("SELECT count(myo_maps_study) FROM myo WHERE myo_maps_study ~ 'MYO[0-9]*U\$' AND myo_date <= ? AND myo_date >= ?");
$sth->execute($date_stop,$date_start) or die "Couldn't execute myo rest tomo query" . $sth->errstr;
my $n_rest_tomo = $sth->fetchrow_array;




print "***** Imaging Statistics  ************\n";
print "n_myo_stress: $n_myo_stress \n";
print "n_myo_rep: $n_myo_rep \n";
print "n_stress_tomo: $n_stress_tomo \n";
print "n_rest_tomo: $n_rest_tomo \n";
print "\n\n***********************************\n";

例如，我是否可以创建一个散列数组，其中键值是n_myo_stress、n_myo_rep等，它们的值是正则表达式MYO0-9\$、MYO0-9*R\$ etc

然后，我是否可以使用$sth->execute(hash value, $date_stop, $date_start)执行数据库查询，并将查询结果赋给形式为$hash_key (即$n_myo_stress)的标量。最后将结果打印到终端

我为糟糕的格式和缩进道歉，我不确定如何在堆栈溢出时做到这一点

Answer 1

你不需要哈希，你可以这样做：

$sth = $dbh->prepare("SELECT count(myo_maps_study) FROM myo WHERE 
        myo_maps_study ~ ? AND myo_date <= ? AND myo_date >= ?");

my @results;

for my $myo (qw(MYO[0-9]*$ MYO[0-9]*R$ MYO[0-9]*T$ MYO[0-9]*U$)) {
    $sth->execute($myo, $date_stop, $date_start) 
        or die "Couldn't execute query for $myo: " . $sth->errstr;
    push @results, $sth->fetchrow_array;
}