FTP and Others
Of what the service of MySql consists?
®it provides a basic servant of usuary and robust data SQL (Structured Query Language) very fast, multi-threaded, multi. The MySQL servant is designed for production surroundings critics, with high service load as well as to integrate itself in software to be distributed. MySQL is a trademark of MySQL AB.
The main characteristics of MySQL
Functions SQL are implemented using an optimized bookstore highly and must be as fast as it is possible. Normally there is no memory reserve after all the boot for consultations.
The servant is available as a separated program to use in network surroundings client/server. Also it is available as library and he can be inlaid (linkado) in independent applications. These applications can be used by themselves or in surroundings where there is network no available.
Types of columns
Diverse types of columns: whole numbers with/without sign of 1, 2, 3, 4, and 8 bytes of length, FLOAT, DOUBLE, CHAR, VARCHAR, TEXT, BLOB, DATE, TIME, DATETIME, TIMESTAMP, YEAR, space SET, ENUM, and types OpenGIS.
Variable length and fixed length records.
Sentences and functions
- > FROM citizen
- > WHERE income/dependents > 10000 AND age > 30;
Complete support for clauses SQL GROUP BY and ORDER BY. Support of functions of grouping (COUNT (), COUNT (DISTINCT…), AVG (), STD (), SUM (), MAX (), MIN (), and GROUP_CONCAT ()).
Support for LEFT OUTER JOIN and RIGHT OUTER JOIN fulfilling standards of syntax SQL and ODBC.
Support for alias in tables and columns as the standard SQL requires it.
DELETE, INSERT, REPLACE, and UPDATE give back the number of rows that they have changed (they have been affected). It is possible to give back the number of rows that would be affected using flag when connecting with the servant.
The specific commando of MySQL SHOW can be used to obtain data about the data base, the basic motor of data, tables and indices. Commando EXPLAIN can be used to determine how the optimizer solves a consultation.
The names of functions do not collide with the names of table or column. For example, ABS is a valid name of column. The only restriction is that for a call to a function, spaces between the function name are not allowed and ‘(’ next.
It can mix tables of different data bases in the same consultation (as in MySQL 3,22).
A system of privileges and passwords that is very flexible and safe, and that it allows verficación based on host. The passwords are safe because all the traffic of passwords is encriptado when it is connected with a servant.
Scalability and limits
Support to great data bases. We use MySQL Server with data bases that contain 50 million registries. Also we know users who use MySQL Server with 60,000 tables and near 5.000.000.000,000 of registries.
They are allowed up to 64 indices by table (32 before MySQL 4.1.2). Each index can consist from 1 to 16 columns or parts of columns. The maximum width of limit is 1000 bytes (500 before MySQL 4.1.2). An index can use area codes of a column for the types of column CHAR, VARCHAR, BLOB, or TEXT.
The clients can connect with the MySQL servant using sockets TCP/IP in any platform. In systems Windows of the NT family (NT, 2000, XP, or 2003), the clients can use named pipes for the connection. In Unix systems, the clients can connect using files socket Unix.
In MySQL 5,0, the servers Windows support connections with shared memory if they initialize themselves with the option --shared-memory. The clients can connect through shared memory using the option --protocol=memory.
The interface for connector ODBC (MyODBC) provides to MySQL has supported for programs clients who use connections ODBC (Open Database Connectivity). For example, it can use MS Access to connect the MySQL servant. The clients can execute themselves in Windows or Unix. The source code of MyODBC is available. All the functions for ODBC 2,5 are supported, as well as many others.
The interface for connector J MySQL provides support for Java clients who use connections JDBC. These clients can execute themselves in Windows or Unix. The source code for connector J is available.
The servant can provide messages of error to the clients in many idomas.
Complete support for different sets from characters, including latin1 (ISO-8859-1), German, big5, ujis, and more. For example, the Scandinavian characters ‘â’, ‘ä’ and ‘ö’ are allowed in names of tables and columns. The support for Unicode is available
All the data keep in the chosen set of characters. All the comparisons for normal columns of chains of characters are marries-insensitive.
The arrangement is realised agreed to the chosen set of characters (using Swedish collation by defect). It is possible to change it when the MySQL servant starts. In order to see an arrangement example very outpost, consults the Czech code of arrangement. MySQL Server supports different sets from characters that must be specified in execution and compile time.
Clients and tools
MySQL server has support commandos SQL to check, to optimize, and to repair tables. These commandos are available through the line of commandos and the client mysqlcheck. MySQL also includes myisamchk, a utility of very fast line of commandos to conduct these operations in MyISAM tables. It consults Chapter 5, Database management.
All the MySQL programs can be invoked with the options --help or -? in order to obtain attendance in line.