MySQL 4.1.0 Alpha

Changelog:

Subqueries:
SELECT * FROM t1 WHERE t1.a=(SELECT t2.b FROM t2);
SELECT * FROM t1 WHERE (1,2,3) IN (SELECT a,b,c FROM t2);
Derived tables:
SELECT t1.a FROM t1, (SELECT * FROM t2) t3 WHERE t1.a=t3.a;
`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 http://www.mysql.com/doc/en/INSERT.html for more info)
A newly designed `GROUP_CONCAT()' aggregate function.
(See http://www.mysql.com/doc/en/Group_by_functions.html for more info)
Extensive Unicode (UTF support.
Character sets can be defined per column, table and database.
`BTREE' index on `HEAP' tables.
Support for OpenGIS (Geographical data).
(See http://www.mysql.com/doc/en/GIS_spatial_extensions_in_MySQL.html for more info)
`SHOW WARNINGS' shows warnings for the last command.
(See http://www.mysql.com/doc/en/SHOW_WARNINGS.html for more info)
Faster binary protocol with prepared statements and parameter binding.
(See http://www.mysql.com/doc/en/C_API_Prepared_statements.html for more info)
Multi-line queries: You can now issue several queries at once and then read the results in one go.
Note C API multiple queries.
(See http://www.mysql.com/doc/en/C_API_multiple_queries.html for more info)
Create Table: `CREATE [TEMPORARY] TABLE [IF NOT EXISTS] table LIKE table'.
Server based `HELP command' that can be used in the `mysql' command line client (and other clients) to get help for SQL commands.