This section lists features implemented in MySQL 4.1.

Support for subqueries and derived tables

• A ``subquery'' is a SELECT statement nested within another statement. A ``derived table'' (an unnamed view) is a subquery in the FROM clause of another statement. See Section 13.1.8, "Subquery Syntax".

Speed enhancements

• Faster binary client/server protocol with support for prepared statements and parameter binding. See Section 24.2.4, "C API Prepared Statements"
• BTREE indexing is supported for HEAP tables, significantly improving response time for non-exact searches.

New functionality

• CREATE TABLE tbl_name2 LIKE tbl_name1 allows you to create, with a single statement, a new table with a structure exactly like that of an existing table
• The MyISAM storage engine supports OpenGIS spatial types for storing geographical data. See Chapter 18, Spatial Extensions in MySQL
• Replication can be done over SSL connections.

Standards compliance, portability, and migration

• The new client/server protocol adds the ability to pass multiple warnings to the client, rather than only a single result. This makes it much easier to track problems that occur in operations such as bulk data loading.
• SHOW WARNINGS shows warnings for the last command. See Section 13.5.4.20, "SHOW WARNINGS Syntax".

Internationalization and Localization

• To support applications that require the use of local languages, the MySQL software offers extensive Unicode support through the utf8 and ucs2 character sets.
• Character sets can be defined per column, table, and database. This allows for a high degree of flexibility in application design, particularly for multi-language Web sites.
• For documentation for this improved character set support, see Chapter 10, Character Set Support.
• Per-connection time zones are supported, allowing individual clients to select their own time zone when necessary.

Usability enhancements

• In response to popular demand, we have added a server-based HELP command that can be used to get help information for SQL statements. The advantage of having this information on the server side is that the information is always applicable to the particular server version that you actually are using. Because this information is available by issuing an SQL statement, any client can be written to access it. For example, the help command of the mysql command-line client has been modified to have this capability.
• In the new client/server protocol, multiple statements can be issued with a single call. See Section 24.2.9, "C API Handling of Multiple Query Execution".
• The new client/server protocol also supports returning multiple result sets. This might occur as a result of sending multiple statements, for example.
• A new INSERT ... ON DUPLICATE KEY UPDATE ... syntax has been implemented. This allows you to UPDATE an existing row if the INSERT would have caused a duplicate in a PRIMARY or UNIQUE index. See Section 13.1.4, "INSERT Syntax".
• A new aggregate function, GROUP_CONCAT(), adds the extremely useful capability of concatenating column values from grouped rows into a single result string. See Section 12.9, "Functions and Modifiers for Use with GROUP BY Clauses".