Sybase1 operates by default on Isolation Level 1, which corresponds (roughly) to MySQL's 'READ COMMITTED'. MySQL2, by default, operates on 'REPEATABLE READ', which corresponds (roughly) to Sybase's Isolation Level 2. Oracle3 operates by default on something similar to Sybase's default isolation level, as does Postgres4.

Now, all four RDBMSes can be set to operate at the level that the SQL92 standard recommends, which is Sybase's Isolation Level 3, or MySQL's 'SERIALIZABLE'. However, only Sybase and MySQL offer the ability to operate at any of the four isolation levels. Oracle8i and Postgres only offer READ COMMITTED and SERIALIZABLE (levels 1 and 3 in Sybase).

  1. the Sybase manual
  2. the MySQL manual
  3. the Oracle manual
  4. the Postgres manual

Note: I couldn't find the official Oracle manuals through Google. I figured something by O'Reilly would be good enough.

Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

In reply to Re^6: Conditional many to many relationships with Class::DBI by dragonchild
in thread Conditional many to many relationships with Class::DBI by BigLug

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.