Here's my suggestion:
firstly use Class::DBI for data access:

package Currency;
use base 'Class::DBI::mysql';

__PACKAGE__->set_db('Main', 'dbi:mysql:dbname', 'user', 'password');
__PACKAGE__->set_up_table("currency");

1;
[download]

Amongst (many) other things, this gives you an easy way to retreive all records in the currency table, or to retreive a particular record given its primary key. Class::DBI has very good documentation.
Now you can use it like this in the view component:

<h3>Currencies:</h3>

<table cellpadding=2>

<tr id=tableheadcolor>
    <th>Currency</th>
    <th>Cid</th>
</tr>

% while (my $currency = $iter->next) {
%    $row++; 
%    $shadetable = ($row % 3 == 0 ? q{id="shadetable"} : "");

     <tr <% $shadetable %>>
       <td>$currency->currency</td>
       <td>$currency->cid</td>
     </tr>
     
% }

</table>

<%once>
use Currency;

my $iter = Currency->retrieve_all;
</%once>

<%init>
my $row=0;
my $shadetable;
</%init>
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And like this in the form component:

<h3>Make a new currency entry</h3>

<form action="comp/insert.mas?form=add_currency" method="post">

    <table cellpadding=2>
    <tr>    
        <td align=right>Currency:</td>
        <td><input name="currency" type="text" value="<% $currency_val
+ %>" size="5"></td>
    </tr>   
    </table>
    <input type="submit">
</form>

<& /view_currency.html &>


<%args>
    $cid => 0
</%args>

<%init>
my $currency_val = "";
if($cid ) {
    $currency_val = Currency->retrieve($cid)->currency;
}
</%init>
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Finally, I'd strongly suggest reading the Mason Book (the whole thing is available to read online).