Re: Database transactions with PEAR DB

On Tue, 2002-01-29 at 16:55, derek fong wrote: > On 1.29.02 8:37 am, "Stig S. Bakken" <ssb@alltheweb.com> wrote: > > > On Tue, 2002-01-29 at 14:23, derek fong wrote: > >> Hello, > >> > >> I have written a PHP application that may be used with either Oracle or > >> MySQL. There is one section of it that would probably benefit from being > >> within a database transaction. Although I've been able to find methods like > >> autoCommit, rollback and commit, I can't seem to find the relevant function > >> to actually start the transaction and finish it off, at least where Oracle > >> is involved. Would it suffice to just set autocommit to false, issue my > >> queries and commit/rollback when I'm done? > >> > >> Can someone shed some light on this? I've read about alternate DB classes I > >> could use, but I would prefer to stick with the PEAR DB class since it's > >> already been used exclusively for the project. > > > > Hi, > > > > Yes, you start a transaction simply by turning off autocommit (which is > > always on by default), and complete it with a call to commit or > > rollback. > > Great! Is there a way to determine whether or not the current RDBMS > actually supports transactions? I see some references to a "provides" > method, but can't actually find it anywhere. I want my app to determine if > the transaction was actually "rolled back" in the database. AFAIK, mysql > 3.23.47 doesn't support real transactions, yet issuing ROLLBACK/COMMIT > statements don't produce errors in the mysql client. Under what > circumstances would the rollback() and commit() functions return error > conditions? If you try doing an operation that the backend database does not support, you will get a DB_ERROR_NOT_CAPABLE error back. Here is "the PEAR way" of handling this error gracefully: $dbh->expectError(DB_ERROR_NOT_CAPABLE); $err = $dbh->autoCommit(false); if (PEAR::isError($err) && $err->getCode() == DB_ERROR_NOT_CAPABLE) { die("whoops, no transaction support!"); } $dbh->popExpect(); The reason for using expectError() and popExpect() is in case you have defined a PEAR error handler, when handling errors gracefully you probably want to avoid it. Just drop the first and last line if you won't need that. - Stig