The main features of MySQL

The following list describes some of the important characteristics of MySQL:

• Fully multi-threaded using kernel threads. That means it easily can use multiple CPUs if available.
• C, C++, Eiffel, Java, Perl, PHP, Python and Tcl APIs. See section 22 MySQL client tools and APIs.
• Works on many different platforms. See section 4.2 Operating systems supported by MySQL.
• Many column types: signed/unsigned integers 1, 2, 3, 4 and 8 bytes long, FLOAT, DOUBLE, CHAR, VARCHAR, TEXT, BLOB, DATE, TIME, DATETIME, TIMESTAMP, YEAR, SET and ENUM types. See section 7.3 Column types.
• Very fast joins using an optimized one-sweep multi-join.
• Full operator and function support in the SELECT and WHERE parts of queries. Example:

  mysql> SELECT CONCAT(first_name, " ", last_name) FROM tbl_name
             WHERE income/dependents > 10000 AND age > 30;
  

• SQL functions are implemented through a highly-optimized class library and should be as fast as they can get! Usually there shouldn't be any memory allocation at all after query initialization.
• Full support for SQL GROUP BY and ORDER BY clauses. Support for group functions (COUNT(), COUNT(DISTINCT), AVG(), STD(), SUM(), MAX() and MIN()).
• Support for LEFT OUTER JOIN with ANSI SQL and ODBC syntax.
• You can mix tables from different databases in the same query (as of version 3.22).
• A privilege and password system which is very flexible and secure, and which allows host-based verification. Passwords are secure because all password traffic when connecting to a server is encrypted.
• ODBC (Open-DataBase-Connectivity) support for Windows95 (with source). All ODBC 2.5 functions and many others. For example, you can use Access to connect to your MySQL server. See section 18 MySQL ODBC Support.
• Very fast B-tree disk tables with index compression.
• 16 indexes per table are allowed. Each index may consist of 1 to 16 columns or parts of columns. The maximum index length is 256 bytes (this may be changed when compiling MySQL). An index may use a prefix of a CHAR or VARCHAR field.
• Fixed-length and variable-length records.
• In-memory hash tables which are used as temporary tables.
• Handles large databases. We are using MySQL with some databases that contain 50,000,000 records.
• All columns have default values. You can use INSERT to insert a subset of a table's columns; those columns that are not explicitly given values are set to their default values.
• Uses GNU Automake, Autoconf, and libtool for portability.
• Written in C and C++. Tested with a broad range of different compilers.
• A very fast thread-based memory allocation system.
• No memory leaks. Tested with a commercial memory leakage detector (purify).
• Includes myisamchk, a very fast utility for table checking, optimization and repair. See section 15 Maintaining a MySQL installation.
• Full support for several different character sets, including ISO-8859-1 (Latin1), big5, ujis, and more. For example, the Scandinavian characters `@ringaccent{a}', `@"a' and `@"o' are allowed in table and column names.
• All data are saved in the chosen character set. All comparisons for normal string columns are case insensitive.
• Sorting is done according to the chosen character set (the Swedish way by default). It is possible to change this when the MySQL server is started up. To see an example of very advanced sorting, look at the Czech sorting code. MySQL supports many different character sets that can be specified at compile and run time.
• Aliases on tables and columns are allowed as in the SQL92 standard.
• DELETE, INSERT, REPLACE, and UPDATE return how many rows were changed (affected). It is possible to return the number of rows matched instead by setting a flag when connecting to the server.
• Function names do not clash with table or column names. For example, ABS is a valid column name. The only restriction is that for a function call, no spaces are allowed between the function name and the `(' that follows it. See section 7.34 Is MySQL picky about reserved words?.
• All MySQL programs can be invoked with the --help or -? options to obtain online assistance.
• The server can provide error messages to clients in many languages. See section 10.1 What languages are supported by MySQL?.
• Clients may connect to the MySQL server using TCP/IP connections or Unix sockets, or named pipes under NT.
• The MySQL-specific SHOW command can be used to retrieve information about databases, tables and indexes. The EXPLAIN command can be used to determine how the optimizer resolves a query.