Beefy Boxes and Bandwidth Generously Provided by pair Networks
The stupid question is the question not asked
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??
Says princepawn:
> How does one write Perl code such that it can work
> without modification in the face of labeling,
> destructive, or positional field mutations?
It's going to take a lot of effort to do it in Perl or in any other language. Here's a small table with only two columns:
ID1 ID2 ----------- 119 666 437 112
Now switch the order of the two columns, and change the names so that ID1 is now called ID2 and ID2 is now called ID1:
ID1 ID2 ----------- 666 119 112 437
Now how are you going to write a program that magically copes with that? This is not a Perl problem; it's an impossible problem. Even looking at the database schema is not going to work.

The only solution is for the database itself to carry its own description. One way is to install a special row into each table:

ID1 ID2 ----------- "id2" "id1" ... ...
then the program can select this row, examine it to see whether the column names or the order have changed, and it can make the appropriate allowances.

In reply to Re: Topics in Perl Programming: Table-Mutation Tolerant Database Fetches with DBI by Dominus
in thread Topics in Perl Programming: Table-Mutation Tolerant Database Fetches with DBI by princepawn

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!
  • 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, 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, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            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.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others pondering the Monastery: (13)
    As of 2014-09-22 13:37 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      How do you remember the number of days in each month?











      Results (192 votes), past polls