If you make email address a primary key on the table storring the information in mysql, it will prevent dups. This may have other effects (performance, etc), i have only used mysql once, so i am not sure. Also, once you do this it will actually error when you try to insert new rows, so it makes it trickier to do inert error checking.

Also, a word of caution, to prevent dup emailing, normalize the email addresses before you load them. This may seem silly, but the RFC allows for the same email address to be written a million ways (well, nearly infinte if you think about number of character/position combonations).

you could also query the whole table out into a hash.BUT i do NOT suggest that ... talk about missing the scalability bus.
i had a memory leak once, and it ruined my favorite shirt.

In reply to Re: Checking for Dupes in MySQL by MZSanford
in thread Checking for Dupes in MySQL by bagelesque

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.