MySQL Reference Manual :: C.2 Changements de la version 4.1.x (Alpha)

Subqueries and derived tables (unnamed views). See Section 14.1.8, « Sous-sélections (SubSELECT) ».

INSERT ... ON DUPLICATE KEY UPDATE ... syntax. This allows you to UPDATE an existing row if the insert would cause a duplicate value in a PRIMARY or UNIQUE key. (REPLACE allows you to overwrite an existing row, which is something entirely different.) See Section 14.1.4, « Syntaxe de INSERT ».

A newly designed GROUP_CONCAT() aggregate function. See Section 13.9, « Fonctions et options à utiliser dans les clauses GROUP BY ».

Extensive Unicode (UTF8) support.

Character sets can be defined per column, table, and database.

New key cache for MyISAM tables with many tunable parameters. You can have multiple key caches, preload index into caches for batches...

BTREE index on HEAP tables.

Support for OpenGIS spatial types (geographical data). See Chapitre 19, Données spatiales avec MySQL.

SHOW WARNINGS shows warnings for the last command. See Section 14.5.3.21, « SHOW WARNINGS | ERRORS ».

Faster binary protocol with prepared statements and parameter binding. See Section 21.2.4, « Fonctions C de commandes préparées ».

You can now issue multiple statements with a single C API call and then read the results in one go. See Section 21.2.8, « Gestion des commandes multiples avec l'interface C ».

Create Table: CREATE [TEMPORARY] TABLE [IF NOT EXISTS] table2 LIKE table1.

Server based HELP command that can be used in the mysql command line client (and other clients) to get help for SQL statements.