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Re: How does DBI return an arrayref with key/value pairs?

by grantm (Parson)
on Jun 24, 2013 at 01:59 UTC ( #1040346=note: print w/replies, xml ) Need Help??

in reply to How does DBI return an arrayref with key/value pairs?

I think you'll find the enlightenment you're after in perlreftut - Mark's very short tutorial about references.

When you called $rows = $dbh->selectall_arrayref, DBI returned a single scalar value which you assigned to $rows. That value was a reference to an array. Each element in that array was a reference to a hash of column names and values.

The array-dereferencing syntax you quoted:

$ { $array_ref } [2]

is exactly equivalent to this syntax:


And in your case would return a hashref.

my $hash_ref = $array_ref->[2]; my $value = $hashref->{$key};

You can also chain together the dereferencing like this:

my $value = $array_ref->[2]->{$key};

And you can even omit the arrow when the initial data structure contains references:

my $value = $array_ref->[2]{$key};

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[choroba]: needed everywhere, available rarely
[LanX]: Question: starting a script from an icon in Windows, but after C-c the window closes ... what I want is to restart in the cmd.exe. Recommendations?
[Corion]: LanX: What do you mean by "restart in the cmd.exe" ?
[Corion]: Do you want to launch a script and keep the command prompt/console window open?
[Corion]: Do you want to wait for a key press before closing the window?
[LanX]: I want the command line in the history
[tye]: -Mouse
[Corion]: Option a) would mean launching cmd.exe /k c:\path\to\ batchfile- launching-perl- script.cmd. Option b) would be to add pause as the last line of said batch file.
[LanX]: First day after holidays ... and already stressed by the fact that colleagues changed stuff without communication ... apparently I'm the only one trying to fight entropy
[Corion]: LanX: The command is always in the history if you typed it in before. If you didn't type the command into the command line, it will not be there. I think there is doskey which can stuff command lines into the history

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