Beefy Boxes and Bandwidth Generously Provided by pair Networks
Your skill will accomplish
what the force of many cannot

Re: For loop suggestions

by roboticus (Chancellor)
on Jan 11, 2013 at 11:45 UTC ( #1012867=note: print w/replies, xml ) Need Help??

in reply to For loop suggestions


Ah, ignore me. I didn't read the original post closely enough, and answered the wrong question.

If you mean SQL database when you say database, then you can ask the database directly with something like:

... use DBI; ... my $DB = DBI->connect(...); my $ar = $DB->selectall_arrayref(<<EOSQL); SELECT min(colName) AS min_val, max(colName) AS max_val FROM tableName EOSQL print "Minimum value found: $$ar[0][0]\n" . "Maximum value found: $$ar[0][1]\n";

Typically, database engines keep statistics about table columns so they can optimize queries, so the database engine many not even have to scan through the table to find all the values.

On the other hand, if you're using a flat file, or a data structure in memory, your approach is almost good. But rather than scanning all possible values, you could just scan the records and track the minimum and maximum values:

my ($min, $max); for my $rec (@records) { $min = $$rec[$colNum] if !defined($min) or $$rec[$colNum]<$min; $max = $$rec[$colNum] if !defined($max) or $$rec[$colNum]>$max; } print "Values used are between $min and $max\n";


When your only tool is a hammer, all problems look like your thumb.

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1012867]
Corion resurfaces. I find the Canary Islands always relaxing, at least for 7 days :)

How do I use this? | Other CB clients
Other Users?
Others having an uproarious good time at the Monastery: (6)
As of 2018-02-21 20:11 GMT
Find Nodes?
    Voting Booth?
    When it is dark outside I am happiest to see ...

    Results (287 votes). Check out past polls.