Associative array - PERL - arrays

Question

I need to know the way of creating the Associative array in Perl.
Basically now I have the code which is implemented as follows:
my $getEmployeeListOfTeamQuery = "SELECT profiles.userid
FROM user_group_map,profiles
WHERE user_group_map.group_id = $teamId
AND profiles.userid = user_group_map.user_id
AND profiles.active = 'y'
AND profiles.login_name NOT LIKE 'qa_%'
AND profiles.disabledtext = ''
GROUP BY profiles.login_name
ORDER BY profiles.login_name";
my $getEmployeeListOfTeam = $dbh->prepare($getEmployeeListOfTeamQuery);
$getEmployeeListOfTeam -> execute();
my #techs = ();
while(my ($tech) - $getEmployeeListOfTeam->fetchrow_array) {
push #techs,$tech;
}
So above code will be having the query in $getEmployeeListOfTeamQuery, Created the array names as techs.
Then tried pushing the values in to the the array.
Here it is working fine.
My question here is regarding the creation of associative array.
That is I need to query as follows : "SELECT profiles.userid, profiles,username....."
Hence I need to create a Associative array with "userid" as key and "username" as value.

Answer 1

I worry about the resources that you are using to learn Perl. Perl programmers haven't used the term "associative array" since Perl 5 was released over twenty years ago. We now call these structures "hashes". If you're learning from resources that use the term "associative array", then they are almost certainly horribly outdated.
But, to answer your question. The code is pretty simple.
my $sql = 'select profiles.userid, profiles.username...';
my $sth = $dbh->prepare($sql);
$sth->execute;
my %techs_hash;
while (my #row = $sth->fetchrow_array) {
$techs_hash{$row[0]} = $row[1];
}

Answer 2

Use selectcol_arrayref() and the Columns attribute:
my $aref = $dbh->selectcol_arrayref('select userid, login_name ...', {Columns => [1, 2]});
my %hash = #$aref;

Answer 3

you can fetch all rows into hash of hashes by one call to selectall_hashref:
my $tech=$dbh->selectall_hashref("select profile.userid, profiles.username, ...",'userid');
or you can fetch all rows into array of hashes with selectall_arrayref with attribute {Slice=>{}} :
my $tech=$dbh->selectall_arrayref("select profile.userid, profiles.username, ...",{Slice=>{}});
and then turn it into desired hash (this is exactly what you want):
my $result;
$result->{$_->{userid}}=$_->{username} foreach #$tech;

Answer 4

my #l;
while(my $h = $sth->fetchrow_hashref){
push #l,$h;
}
my %hash;
map { $hash{$_->{userid}} = $_->{username} } #l;