php extension MySQLi-Mysql Tutorial-php.cn

The mysqli extension allows us to access the functionality provided by MySQL 4.1 and above.

mysqli extension and persistent connections

The persistent connection of the mysqli extension was introduced in PHP5.3. Support already exists in PDO MYSQL and ext/mysql. The idea behind persistent connections is that the connection between the client process and the database can be maintained and reused through a client process, rather than being created and destroyed multiple times. This reduces the overhead of needing to create a new connection each time, and unused connections are cached and ready for reuse.

Unlike the mysql extension, mysqli does not provide a special method for opening a persistent connection. When you need to open a persistent connection, you must add p: before the host name when connecting.

The problem with using persistent connections is that they can be in an unpredictable state on the client side. For example, a table lock might be activated before the client terminates unexpectedly. A new client process that reuses the persistent connection will get the connection "as is". In this way, a new client process needs to do any possible cleanup work in order to better use persistent connections, which increases the burden on the programmer.

The persistent connection of the mysqli extension provides built-in cleanup processing code. The cleanup work done by mysqli includes:

Rolling back active transactions

Close and delete temporary tables

Unlock tables,

Reset session variables

Close prepared statements (often happens in PHP)

Close processing The program

releases the lock acquired via GET_LOCK()

This ensures that the persistent connection returned from the connection pool is in a clean state before the client process uses it.

The mysqli extension completes this cleanup work by automatically calling the C-API function mysql_change_user().

The feature of automatic cleaning has advantages and disadvantages. The advantage is that programmers no longer need to worry about additional cleanup code because they are called automatically. However, the disadvantage is that the code may be potentially slower because the cleanup code needs to be executed every time a connection is returned from the connection pool.

This automatic cleaning code can be turned off by defining MYSQLI_NO_CHANGE_USER_ON_PCONNECT when compiling php.

The mysqli extension supports persistent connections when using Mysql Native Driver or Mysql Client Library (libmysql).

MySQLi class

represents a connection between PHP and Mysql database.

mysqli::$affected_rows — Gets the number of affected rows in a previous MySQL operation

mysqli::autocommit — Turn on or off the automatic command commit transaction mode of this database connection

mysqli::begin_transaction — Starts a transaction

mysqli::change_user — Changes the user of the specified database connection

mysqli::character_set_name — Returns the default character encoding of the current database connection

mysqli::$client_info — Get MySQL client info

mysqli::$client_version — Returns the MySQL client version as a string

mysqli::close — Close a previously opened database connection

mysqli::commit — Commit a transaction

mysqli::$connect_errno — Returns the error code from last connect call

mysqli: :$connect_error — Returns a string description of the last connect error

mysqli::__construct — Open a new connection to the MySQL server

mysqli::debug — Performs debugging operations

mysqli::dump_debug_info — Output debugging information to Log

mysqli::errno — Returns the error code of the most recent function call

mysqli::$error_list — Returns a list of errors from the last command executed

mysqli::$error — Returns a string description of the last error

mysqli::$field_count — Returns the number of columns for the most recent query

mysqli::get_charset — Returns a character set object

mysqli::get_client_info — Get MySQL client info

mysqli_get_client_stats — Returns client per-process statistics

mysqli_get_client_version — Returns the MySQL client version as an integer

mysqli::get_connection_stats — Returns statistics about the client connection

mysqli::$host_info — Returns a string representing the type of connection used

mysqli::$protocol_version — Returns the version of the MySQL protocol used

mysqli::$server_info — Returns the version of the MySQL server

mysqli::$server_version — Returns the version of the MySQL server as an integer

mysqli::get_warnings — Get result of SHOW WARNINGS

mysqli::$info — Retrieves information about the most recently executed query

mysqli::init — Initializes MySQLi and returns a resource for use with mysqli_real_connect()

mysqli::$insert_id — Returns the auto generated id used in the last query

mysqli::kill — Asks the server to kill a MySQL thread

mysqli::more_results — Check if there are any more query results from a multi query

mysqli::multi_query — Performs a query on the database

mysqli::next_result — Prepare next result from multi_query

mysqli::options — Set options

mysqli::ping — Pings a server connection, or tries to reconnect if the connection has gone down

mysqli::poll — Poll connections

mysqli::prepare — Prepare an SQL statement for execution

mysqli::query — 对数据库执行一次查询

mysqli::real_connect — Opens a connection to a mysql server

mysqli::real_escape_string — Escapes special characters in a string for use in an SQL statement, taking into account the current charset of the connection

mysqli::real_query — 执行一个mysql查询

mysqli::reap_async_query — Get result from async query

mysqli::refresh — Refreshes

mysqli::release_savepoint — Rolls back a transaction to the named savepoint

mysqli::rollback — 回退当前事务

mysqli::rpl_query_type — Returns RPL query type

mysqli::savepoint — Set a named transaction savepoint

mysqli::select_db — 选择用于数据库查询的默认数据库

mysqli::send_query — 发送请求并返回结果

mysqli::set_charset — 设置默认字符编码

mysqli::set_local_infile_default — Unsets user defined handler for load local infile command

mysqli::set_local_infile_handler — Set callback function for LOAD DATA LOCAL INFILE command

mysqli::$sqlstate — Returns the SQLSTATE error from previous MySQL operation

mysqli::ssl_set — Used for establishing secure connections using SSL

mysqli::stat — Gets the current system status

mysqli::stmt_init — 初始化一条语句并返回一个用于mysqli_stmt_prepare(调用)的对象

mysqli::store_result — Transfers a result set from the last query

mysqli::$thread_id — Returns the thread ID for the current connection

mysqli::thread_safe — 返回是否是线程安全的

mysqli::use_result — Initiate a result set retrieval

mysqli::$warning_count — Returns the number of warnings from the last query for the given link

MySQLi_STMT类

代表一个prepared语句。

mysqli_stmt::$affected_rows — Returns the total number of rows changed, deleted, or inserted by the last executed statement

mysqli_stmt::attr_get — Used to get the current value of a statement attribute

mysqli_stmt::attr_set — Used to modify the behavior of a prepared statement

mysqli_stmt::bind_param — Binds variables to a prepared statement as parameters

mysqli_stmt::bind_result — Binds variables to a prepared statement for result storage

mysqli_stmt::close — Closes a prepared statement

mysqli_stmt::data_seek — Seeks to an arbitrary row in statement result set

mysqli_stmt::$errno — Returns the error code for the most recent statement call

mysqli_stmt::$error_list — Returns a list of errors from the last statement executed

mysqli_stmt::$error — Returns a string description for last statement error

mysqli_stmt::execute — Executes a prepared Query

mysqli_stmt::fetch — Fetch results from a prepared statement into the bound variables

mysqli_stmt::$field_count — Returns the number of field in the given statement

mysqli_stmt::free_result — Frees stored result memory for the given statement handle

mysqli_stmt::get_result — Gets a result set from a prepared statement

mysqli_stmt::get_warnings — Get result of SHOW WARNINGS

mysqli_stmt::$insert_id — Get the ID generated from the previous INSERT operation

mysqli_stmt::more_results — Check if there are more query results from a multiple query

mysqli_stmt::next_result — Reads the next result from a multiple query

mysqli_stmt::$num_rows — Return the number of rows in statements result set

mysqli_stmt::$param_count — Returns the number of parameter for the given statement

mysqli_stmt::prepare — Prepare an SQL statement for execution

mysqli_stmt::reset — Resets a prepared statement

mysqli_stmt::result_metadata — Returns result set metadata from a prepared statement

mysqli_stmt::send_long_data — Send data in blocks

mysqli_stmt::$sqlstate — Returns SQLSTATE error from previous statement operation

mysqli_stmt::store_result — Transfers a result set from a prepared statement

mysqli_result类

代表从一个数据库查询中获取的结果集

mysqli_result::$current_field — Get current field offset of a result pointer

mysqli_result::data_seek — Adjusts the result pointer to an arbitrary row in the result

mysqli_result::fetch_all — Fetches all result rows as an associative array, a numeric array, or both

mysqli_result::fetch_array — Fetch a result row as an associative, a numeric array, or both

mysqli_result::fetch_assoc — Fetch a result row as an associative array

mysqli_result::fetch_field_direct — Fetch meta-data for a single field

mysqli_result::fetch_field — Returns the next field in the result set

mysqli_result::fetch_fields — Returns an array of objects representing the fields in a result set

mysqli_result::fetch_object — Returns the current row of a result set as an object

mysqli_result::fetch_row — Get a result row as an enumerated array

mysqli_result::$field_count — Get the number of fields in a result

mysqli_result::field_seek — Set result pointer to a specified field offset

mysqli_result::free — Frees the memory associated with a result

mysqli_result::$lengths — Returns the lengths of the columns of the current row in the result set

mysqli_result::$num_rows — Gets the number of rows in a result

MySQLi_Driver类

MySQLi 驱动.

client_info

客户端API头版本（比如：(string)"5.1.49"）

client_version

客户端版本（比如：(int)50149）

driver_version

Mysqli驱动版本（比如：(int)101009）

embedded

是否开启了MySQLi嵌入式支持。

reconnect

允许或阻止重连接（查看INI指令中的mysqli.reconnect）

report_mode

设置为MYSQLI_REPORT_OFF, MYSQLI_REPORT_ALL或者 MYSQLI_REPORT_STRICT （为错误抛出异常，译注：需要和MYSQLI_REPORT_ERROR联合使用）, MYSQLI_REPORT_ERROR (报告MYSQL错误)和 MYSQLI_REPORT_INDEX (报告索引相关的错误)的任意组合。

mysqli_driver::embedded_server_end — Stop embedded server

mysqli_driver::embedded_server_start — Initialize and start embedded server

mysqli_driver::$report_mode — Enables or disables internal report functions

MySQLi_Warning类

代表一个Mysql警告。

message

消息字符串

sqlstate

SQL状态

errno

错误编号

mysqli_warning::__construct — The __construct purpose

mysqli_warning::next — The next purpose

mysqli_sql_exception类

mysqli异常处理类

mysqli_sql_exception extends RuntimeException {
    /* 属性 */
    protected string $sqlstate ;
    /* 继承的属性 */
    protected string $message ;
    protected int $code ;
    protected string $file ;
    protected int $line ;
}

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别名和过时的Mysqli 函数

mysqli_bind_param — mysqli_stmt_bind_param的别名

mysqli_bind_result — mysqli_stmt_bind_result的别名

mysqli_client_encoding — mysqli_character_set_name的别名

mysqli_connect — 别名 mysqli::__construct

mysqli::disable_reads_from_master — Disable reads from master

mysqli_disable_rpl_parse — 禁用RPL解析

mysqli_enable_reads_from_master — 开启从主机读取

mysqli_enable_rpl_parse — 开启RPL解析

mysqli_escape_string — 别名 mysqli_real_escape_string

mysqli_execute — mysqli_stmt_execute的别名