Why does MySQL allow “group by” queries WITHOUT aggregate functions?
According to this page (the 5.0 online manual), it’s for better performance and user convenience.
ansi-sql
Why isn’t SQL ANSI-92 standard better adopted over ANSI-89?
According to “SQL Performance Tuning” by Peter Gulutzan and Trudy Pelzer, of the six or eight RDBMS brands they tested, there was no difference in optimization or performance of SQL-89 versus SQL-92 style joins. One can assume that most RDBMS engines transform the syntax into an internal representation before optimizing or executing the query, so … Read more