As moritz suggested, using exceptions can simplify your logic:

$dbh->{RaiseError} = 1; # only need to do this once
...
eval {
  my $sth = $dbh->prepare(...);
  $sth->execute(...);
};
if ($@) {
  # unable to insert, error message is in $@
  ...
}
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There are a couple of things that I would recommend:

1. First, when posting code in your question, please wrap it in <code> ... </code> tags, so that it is easier to read.
2. Second, it is generally a best practice to use placeholders in your query, and pass the values as arguments.

See What are placeholders in DBI, and why would I want to use them? for more information about placeholders.

Concurring with the RaiseError, placeholder, and code tag suggestions, let me also note that there's no need to call finish on DML statements (inserts and updates).

Here's what your code will look like if you follow the advice above:

my @fields = qw(
    ict_category
    ict_type
    ict_subtype
    ict_instance
    ict_assign2_grp
    ict_severity_lvl
    ict_date
);
my @placeholders = map {'?'} @fields;
{ local $" = ',';
  $sqlwi = "INSERT INTO $ICT (@fields) 
  VALUES(@placeholders)";
}

$dbh->{RaiseError} = 1;
eval {
    my $sth = $dbh->prepare($sqlwi);
    $sth->execute(
        $a_catg,
        $a_type,
        $a_styp,
        $a_inst,
        $a_agrp,
        $a_sevl,
        $dat3,
    );
};
if ($@) {
  # unable to insert, error message is in $@
  ...
}
[download]

Thank you for investing in me, this example is most helpful, I appreciate it.

Also, instead of the custom error message, use the one DBI gives you with DBI->errtsr

update: Thanks Crackers2 and Narveson, you are absolutely right. Please ignore this post.

You are trying to build your query based on the values that those $a_* variables have. But you are passing them inside single quotes, and what goes inside single quotes is not interpolated.

No, only the outermost quotes determine whether interpolation will happen or not. Since those are double quotes it will work fine. Minimal example:

my $var = test';
my $result = "This is a '$var' again";
print "$result\n";
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$var will be interpolated and This is a 'test' again will be printed.

But you are passing them inside single quotes, and what goes inside single quotes is not interpolated.

Wrong. The single quotes are inside a double-quoted string.

The original version is not best practice, but it won't fail until one of the interpolated variables contains an embedded quote.

my $name = 'Larry';
my $sql = "Insert into Users (name) values ('$name')";
print $sql;
# Insert into Users (name) values ('Larry')
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