1.6.1 Features Available in MySQL 4.1

The features listed in this section are implemented in MySQL 4.1. A few other features are still planned for MySQL 4.1. See section 1.9.1 New Features Planned For 4.1.

Most new features being coded, such as stored procedures, will be available in MySQL 5.0. See section 1.9.2 New Features Planned For 5.0.

Support for subqueries and derived tables

• Subqueries are now supported. Here is an example:

  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 (unnamed views) are now supported. Basically, a derived table is a subquery in the FROM clause of a SELECT statement. Here is an example:

  SELECT t1.a FROM t1, (SELECT * FROM t2) t3 WHERE t1.a=t3.a;
  

Speed enhancements

• Faster binary protocol with prepared statements and parameter binding. See section 9.1.4 C API Prepared Statements.
• BTREE indexing is now supported for HEAP tables, significantly improving response time for non-exact searches.

New functionality

• CREATE TABLE table LIKE table allows you to create a new table with the exact structure of an existing table, using a single command.
• Support for OpenGIS (Geographical data). See section 11 Spatial Extensions in MySQL.

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 jobs such as bulk loading of data much easier to track. SHOW WARNINGS shows warnings for the last command. See section 4.5.7.9 SHOW WARNINGS | ERRORS.

Internationalisation

• To support our ever expanding user base using local languages in applications, the MySQL software now offers extensive Unicode (UTF8) support.
• Character sets can now be defined per column, table, and database. This allows for a high degree of flexibility in application design, particularly for multi-language web sites.
• The documentation for this improved character set support is being developed and will be added to the manual soon.

Usability enhancements

• In response to popular demand, we have added a server-based HELP command that can be used in the mysql command line client (and other clients) to get help for SQL commands. The advantage of having this information on the server side is that the information is always applicable for that particular server version.
• In the new client/server protocol, multi-line queries can now be enabled. This allows you to issue several queries in a single call and then read all the results in one go. See section 9.1.8 C API Handling of Multiple Query Execution.
• 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 key (index). See section 6.4.3 INSERT Syntax.
• We have designed a new aggregate function GROUP_CONCAT(), adding the extremely useful capability of concatenating columns from grouped rows into a single result string. See section 6.3.7 Functions and Modifiers for Use with GROUP BY Clauses.
• The new client/server protocol supports multiple result sets.

The news section in this manual includes a more in-depth list of features. See section D.2 Changes in release 4.1.x (Alpha).

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