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# XCIII. MySQL Improved Extension

# Introduction

The mysqli extension allows you to access the functionality provided by MySQL 4.1 and above. More information about the MySQL Database server can be found at http://www.mysql.com/

Documentation for MySQL can be found at http://dev.mysql.com/doc/.

Parts of this documentation included from MySQL manual with permissions of MySQL AB.

# Requirements

In order to have these functions available, you must compile PHP with support for the mysqli extension.

> Note: The mysqli extension is designed to work with the version 4.1.3 or above of MySQL. For previous versions, please see the MySQL extension documentation.

# Installation

To install the mysqli extension for PHP, use the --with-mysqli=mysql_config_path/mysql_config configuration option where mysql_config_path represents the location of the mysql_config program that comes with MySQL versions greater than 4.1.

If you would like to install the mysql extension along with the mysqli extension you have to use the same client library to avoid any conflicts.

# Runtime Configuration

The behaviour of these functions is affected by settings in `php.ini`.

Table 1. MySQLi Configuration Options

Name | Default | Changeable | Changelog
--- | --- | --- | ---
mysqli.max_links | "-1" | PHP_INI_SYSTEM | Available since PHP 5.0.0.
mysqli.default_port | "3306" | PHP_INI_ALL | Available since PHP 5.0.0.
mysqli.default_socket | NULL | PHP_INI_ALL | Available since PHP 5.0.0.
mysqli.default_host | NULL | PHP_INI_ALL | Available since PHP 5.0.0.
mysqli.default_user | NULL | PHP_INI_ALL | Available since PHP 5.0.0.
mysqli.default_pw | NULL | PHP_INI_ALL | Available since PHP 5.0.0.

For further details and definitions of the above PHP_INI_* constants, see the chapter on configuration changes.

Here's a short explanation of the configuration directives.

mysqli.max_links integer

  The maximum number of MySQL connections per process.

mysqli.default_port string

  The default TCP port number to use when connecting to the database server if no other port is specified. If no default is specified, the port will be obtained from the MYSQL_TCP_PORT environment variable, the mysql-tcp entry in `/etc/services` or the compile-time MYSQL_PORT constant, in that order. Win32 will only use the MYSQL_PORT constant.

mysqli.default_socket string

  The default socket name to use when connecting to a local database server if no other socket name is specified.

mysqli.default_host string

  The default server host to use when connecting to the database server if no other host is specified. Doesn't apply in safe mode.

mysqli.default_user string

  The default user name to use when connecting to the database server if no other name is specified. Doesn't apply in safe mode.

mysqli.default_pw string

  The default password to use when connecting to the database server if no other password is specified. Doesn't apply in safe mode.

# Predefined Classes

## mysqli

Represents a connection between PHP and a MySQL database.

### Constructor

- mysqli - construct a new mysqli object

### Methods

- autocommit - turns on or off auto-commiting database modifications

- change_user - changes the user of the specified database connection

- character_set_name - returns the default character set for the database connection

- close - closes a previously opened connection

- commit - commits the current transaction

- connect - opens a new connection to MySQL database server

- debug - performs debugging operations

- dump_debug_info - dumps debug information

- get_client_info - returns client version

- get_host_info - returns type of connection used

- get_server_info - returns version of the MySQL server

- get_server_version - returns version of the MySQL server

- init - initializes mysqli object

- info - retrieves information about the most recently executed query

- kill - asks the server to kill a mysql thread

- multi_query - performs multiple queries

- more_results - check if more results exist from currently executed multi-query

- next_result - reads next result from currently executed multi-query

- options - set options

- ping - pings a server connection or reconnects if there is no connection

- prepare - prepares a SQL query

- query - performs a query

- real_connect - attempts to open a connection to MySQL database server

- escape_string - escapes special characters in a string for use in a SQL statement, taking into account the current charset of the connection

- rollback - rolls back the current transaction

- select_db - selects the default database

- set_charset - sets the default client character set

- ssl_set - sets ssl parameters

- stat - gets the current system status

- stmt_init- initializes a statement for use with mysqli_stmt_prepare

- store_result - transfers a resultset from last query

- thread_safe - returns whether thread safety is given or not

- use_result - transfers an unbuffered resultset from last query

### Properties

- affected_rows - gets the number of affected rows in a previous MySQL operation

- client_info - returns the MySQL client version as a string

- client_version - returns the MySQL client version as an integer

- errno - returns the error code for the most recent function call

- error - returns the error string for the most recent function call

- field_count - returns the number of columns for the most recent query

- host_info - returns a string representing the type of connection used

- info - retrieves information about the most recently executed query

- insert_id - returns the auto generated id used in the last query

- protocol_version - returns the version of the MySQL protocol used

- server_info - returns a string that represents the server version number

- server_version - returns the version number of the server as an integer

- sqlstate - returns a string containing the SQLSTATE error code for the last error

- thread_id - returns the thread ID for the current connection

- warning_count - returns the number of warnings generated during execution of the previous SQL statement

## mysqli_stmt

Represents a prepared statement.

### Methods

- bind_param - binds variables to a prepared statement

- bind_result - binds variables to a prepared statement for result storage

- close - closes a prepared statement

- data_seek - seeks to an arbitrary row in a statement result set

- execute - executes a prepared statement

- fetch - fetches result from a prepared statement into bound variables

- free_result - frees stored result memory for the given statement handle

- prepare - prepares a SQL query

- reset - resets a prepared statement

- result_metadata - retrieves a resultset from a prepared statement for metadata information

- send_long_data - sends data in chunks

- store_result - buffers complete resultset from a prepared statement

### Properties

- affected_rows - returns affected rows from last statement execution

- errno - returns errorcode for last statement function

- error - returns errormessage for last statement function

- field_count - returns the number of columns in a result set

- id - returns the statement identifier

- insert_id - returns the value generated for an AUTO_INCREMENT column by the prepared statement

- num_rows - returns the number of rows in the result set

- param_count - returns number of parameter for a given prepare statement

- sqlstate - returns a string containing the SQLSTATE error code for the last statement function

## mysqli_result

Represents the result set obtained from a query against the database.

### Methods

- close - closes resultset

- data_seek - moves internal result pointer

- fetch_array - fetches a result row as an associative array, a numeric array, or both.

- fetch_assoc - fetches a result row as an associative array

- fetch_field - gets column information from a resultset

- fetch_fields - gets information for all columns from a resulset

- fetch_field_direct - gets column information for specified column

- fetch_object - fetches a result row as an object

- fetch_row - gets a result row as an enumerated array

- field_seek - set result pointer to a specified field offset

- free_result - frees result memory

### Properties

- current_field - returns offset of current fieldpointer

- field_count - returns number of fields in resultset

- lengths - returns an array of columnlengths

- num_rows - returns number of rows in resultset

- type - returns `MYSQLI_STORE_RESULT` or `MYSQLI_USE_RESULT`

# Predefined Constants

Table 2. MySQLi Constants

Name | Description
--- | ---
`MYSQLI_READ_DEFAULT_GROUP` (integer) | Read options from the named group from `my.cnf' or the file specified with MYSQLI_READ_DEFAULT_FILE
`MYSQLI_READ_DEFAULT_FILE` (integer) | Read options from the named option file instead of from my.cnf
`MYSQLI_OPT_CONNECT_TIMEOUT` (integer) | Connect timeout in seconds
`MYSQLI_OPT_LOCAL_INFILE` (integer) | Enables command LOAD LOCAL INFILE
`MYSQLI_INIT_COMMAND` (integer) | Command to execute when connecting to MySQL server. Will automatically be re-executed when reconnecting.
`MYSQLI_CLIENT_SSL` (integer) | Use SSL (encrypted protocol). This option should not be set by application programs; it is set internally in the MySQL client library
`MYSQLI_CLIENT_COMPRESS` (integer) | Use compression protocol
`MYSQLI_CLIENT_INTERACTIVE` (integer) | Allow interactive_timeout seconds (instead of wait_timeout seconds) of inactivity before closing the connection. The client's session wait_timeout variable will be set to the value of the session interactive_timeout variable.
`MYSQLI_CLIENT_IGNORE_SPACE` (integer) | Allow spaces after function names. Makes all functions names reserved words.
`MYSQLI_CLIENT_NO_SCHEMA` (integer) | Don't allow the db_name.tbl_name.col_name syntax.
`MYSQLI_CLIENT_MULTI_QUERIES` (integer) |
`MYSQLI_STORE_RESULT` (integer) | For using buffered resultsets
`MYSQLI_USE_RESULT` (integer) | For using unbuffered resultsets
`MYSQLI_ASSOC` (integer) | Columns are returned into the array having the fieldname as the array index.
`MYSQLI_NUM` (integer) | Columns are returned into the array having an enumerated index.
`MYSQLI_BOTH` (integer) | Columns are returned into the array having both a numerical index and the fieldname as the associative index.
`MYSQLI_NOT_NULL_FLAG` (integer) | Indicates that a field is defined as NOT NULL
`MYSQLI_PRI_KEY_FLAG` (integer) | Field is part of a primary index
`MYSQLI_UNIQUE_KEY_FLAG` (integer) | Field is part of a unique index.
`MYSQLI_MULTIPLE_KEY_FLAG` (integer) | Field is part of an index.
`MYSQLI_BLOB_FLAG` (integer) | Field is defined as BLOB
`MYSQLI_UNSIGNED_FLAG` (integer) | Field is defined as UNSIGNED
`MYSQLI_ZEROFILL_FLAG` (integer) | Field is defined as ZEROFILL
`MYSQLI_AUTO_INCREMENT_FLAG` (integer) | Field is defined as AUTO_INCREMENT
`MYSQLI_TIMESTAMP_FLAG` (integer) | Field is defined as TIMESTAMP
`MYSQLI_SET_FLAG` (integer) | Field is defined as SET
`MYSQLI_NUM_FLAG` (integer) | Field is defined as NUMERIC
`MYSQLI_PART_KEY_FLAG` (integer) | Field is part of an multi-index
`MYSQLI_GROUP_FLAG` (integer) | Field is part of GROUP BY
`MYSQLI_TYPE_DECIMAL` (integer) | Field is defined as DECIMAL
`MYSQLI_TYPE_NEWDECIMAL` (integer) | Precision math DECIMAL or NUMERIC field (MySQL 5.0.3 and up)
`MYSQLI_TYPE_BIT` (integer) | Field is defined as BIT (MySQL 5.0.3 and up)
`MYSQLI_TYPE_TINY` (integer) | Field is defined as TINYINT
`MYSQLI_TYPE_SHORT` (integer) | Field is defined as INT
`MYSQLI_TYPE_LONG` (integer) | Field is defined as INT
`MYSQLI_TYPE_FLOAT` (integer) | Field is defined as FLOAT
`MYSQLI_TYPE_DOUBLE` (integer) | Field is defined as DOUBLE
`MYSQLI_TYPE_NULL` (integer) | Field is defined as DEFAULT NULL
`MYSQLI_TYPE_TIMESTAMP` (integer) | Field is defined as TIMESTAMP
`MYSQLI_TYPE_LONGLONG` (integer) | Field is defined as BIGINT
`MYSQLI_TYPE_INT24` (integer) | Field is defined as MEDIUMINT
`MYSQLI_TYPE_DATE` (integer) | Field is defined as DATE
`MYSQLI_TYPE_TIME` (integer) | Field is defined as TIME
`MYSQLI_TYPE_DATETIME` (integer) | Field is defined as DATETIME
`MYSQLI_TYPE_YEAR` (integer) | Field is defined as YEAR
`MYSQLI_TYPE_NEWDATE` (integer) | Field is defined as DATE
`MYSQLI_TYPE_ENUM` (integer) | Field is defined as ENUM
`MYSQLI_TYPE_SET` (integer) | Field is defined as SET
`MYSQLI_TYPE_TINY_BLOB` (integer) | Field is defined as TINYBLOB
`MYSQLI_TYPE_MEDIUM_BLOB` (integer) | Field is defined as MEDIUMBLOB
`MYSQLI_TYPE_LONG_BLOB` (integer) | Field is defined as LONGBLOB
`MYSQLI_TYPE_BLOB` (integer) | Field is defined as BLOB
`MYSQLI_TYPE_VAR_STRING` (integer) | Field is defined as VARCHAR
`MYSQLI_TYPE_STRING` (integer) | Field is defined as CHAR
`MYSQLI_TYPE_GEOMETRY` (integer) | Field is defined as GEOMETRY
`MYSQLI_NEED_DATA` (integer) | More data available for bind variable
`MYSQLI_NO_DATA` (integer) | No more data available for bind variable
`MYSQLI_DATA_TRUNCATED` (integer) | Data truncation occurred. Available since PHP 5.1.0 and MySQL 5.0.5.

# Examples

All Examples in the MySQLI documentation use the world database from MySQL AB. The world database can be found at http://dev.mysql.com/get/Downloads/Manual/world.sql.gz/from/pick

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