Odp: [PHP-DB] Re: PostgreSQL versus MySQL

Od: "Bob Hall" <rjhalljr@starpower.net> Temat: Re: [PHP-DB] Re: PostgreSQL versus MySQL > > > The implication is that MySQL is not an RDBMS. The only attempt I > > > know of to define an RDBMS was Codd's, and no DBMS has ever met the > > > criteria he published in a paper in the late 80s (1986?). Even though > > > Oracle doesn't meet the criteria of the best known definition (only > > > definition?) of an RDBMS, we all seem to agree that Oracle is an > > > RDBMS. An RDBMS is a DBMS designed to manage a relational database, > > > and a database is relational because it stores data in linked, > > > normalized tables. > > > >The only thing I question in this is that without transaction support, > >what exactly is MySQL "managing"? > > The data in the normalized tables. Of 12 Codd's rules (1985), MySQL doesn't meet four: 5 - full internal language implementation with transactional processing support; 6 - using views for data modification; 10 - autonomous referential integrity mechanism built into database; 11 - autonomous data distribution. Of SQL-92 instructions MySQL doesn't implement following: CREATE | DROP SCHEMA, DECLARE LOCAL TEMPORARY TABLE, CREATE | ALTER | DROP DOMAIN, CREATE | DROP CHARACTER SET, CREATE | DROP COLLATION, CREATE | DROP TRANSLATION, CREATE | DROP VIEW, ALLOCATE | DECLARE | OPEN | CLOSE CURSOR, COMMIT, ROLLBACK, FETCH, CLOSE, CREATE | DROP ASSERTION, SET CONSTRAINTS MODE, SET SESSION AUTHORIZATION, SET TRANSACTION MODE, SET NAMES, SET SCHEMA, SET TIME ZONE, ALLOCATE | SET | GET | DEALLOCATE DESCRIPTOR, DESCRIBE, PREPARE, DEALLOCATE PREPARE, EXECUTE, EXECUTE IMMEDIATE, GET DIAGNOSTICS This set is about 85% of SQL-92 standart, but i didn't see any DBMS that implements that all. Of SQL-92 keywords, about 65% is absent in MySQL, but they are not too often used even if they are present with significant exception of trigger and procedural language. Cheers Jarek Zgoda