DBI:CSV SQL parsing problem

[rlewisuk]

Hello all.

I am having problems with DBI:CSV. I keep getting the following error:

"SQL ERROR: Bad table or column name 'col2 + col3' has chars not alphanumeric or underscore!
DBD::CSV::db prepare failed: SQL ERROR: Bad table or column name 'col2 + col3' has chars not alphanumeric or underscore!
for Statement "SELECT AVG(col2 + col3) FROM mydata.csv" at test_script.pl line 11."

I have the following code to query a csv file.

#!/usr/bin/perl

use DBI;
use strict;
use warnings;

## Set up connection to csv data file as a database
my $dbh = DBI->connect("dbi:CSV:f_dir=./", "", "",
        {AutoCommit => 1, RaiseError => 1});

my $sth = $dbh->prepare("SELECT AVG(col2 + col3) FROM mydata.csv");
$sth->execute();
my $value = $sth->fetchrow_array;

foreach (@value){
    print $_."\n";
}

$sth->finish();
$dbh->disconnect();

This works fine:

my $sth = $dbh->prepare("SELECT AVG(col3) FROM mydata.csv");

So does this:

my $sth = $dbh->prepare("SELECT (col2 + col3) FROM mydata.csv");

Just not this:

my $sth = $dbh->prepare("SELECT AVG(col2 + col3) FROM mydata.csv");

The mydata.csv file has the following in it:

col1,col2,col3,col4

575,480,192,5

388,485,194,5

379,447,210,5

504,465,215,0.8

356,439,219,0.7

481,435,225,0.6

Any idea what is going wrong? Any help would be appreciated.