use Perl

• JOIN and optimizations (Score:1)

  by iburrell (4155)

  There are two reasons I have encountered for implicit joins. Some systems don't support the synrax. SQL::Statement is the one I have encountered.

  Also, some databases don't optimize as well with explicit joins. Until recently, PostgreSQL would not reorder joins and this limited how well the optimizer worked. The most recent version of PostgreSQL fixed this problem. But OUTER JOINs can't be reordered without potentially changing the results.

  I much prefer explicit joins. I think they the queries mu
• easier to learn SQL this way? (Score:1)

  by amackey (4963)

  This is actually how I teach SQL, insisting on the explicit syntax for clarity (and sometimes correctness, as you point out in your example). See sql_tutorial.pdf [virginia.edu] for the material I use. I absolutely forbid the use of commas as join operators.

  Unfortunately, Oracle has no support for standard SQL, using it's own odd syntax for joins (comma-separated tables, and where clauses with optional "+" symbols to denote outer join directions). Ugly.
  • Re:easier to learn SQL this way? (Score:1)

    by amackey (4963)

    Hmm, actually it looks like Oracle 9i has SQL92 support, so nevermind that.