mysqli擴展允許我們訪問mysql?4.1及以上版本提供的功能。?
mysqli擴展和持久化連接
mysqli擴展的持久化連接在PHP5.3中被引入。支持已經存在于PDO MYSQL 和ext/mysql中。持久化連接背后的思想是客戶端進程和數據庫之間的連接可以通過一個客戶端進程來保持重用， 而不是多次的創建和銷毀。這降低了每次需要創建一個新連接的開銷，未使用的連接被緩存起來并且準備隨時被重用。
不像mysql擴展，mysqli沒有提供一個特殊的方法用于打開持久化連接。需要打開一個持久化連接時，你必須在 連接時在主機名前增加p:。
使用持久化連接的問題在于它們可能在客戶端處于不可預知的狀態。比如，一個表鎖可能在客戶端意外終止之前被激活。 一個新的客戶端進程重用這個持久化連接就會”按照原樣”得到這個連接。這樣，一個新的客戶端進程 為了更好的使用持久化連接，就需要做任何可能的清理工作，這樣就增加了對程序員的負擔。
mysqli擴展的持久化連接提供了內建的清理處理代碼。mysqli?所做的清理工作包括：
立即學習“PHP免費學習筆記（深入）”；
回滾活動的事務
關閉并且刪除臨時表
對表解鎖、
重置會話變量
關閉prepared語句（在PHP中經常發生）
關閉處理程序
釋放通過?GET_LOCK()獲得的鎖
這確保了從連接池返回的持久化連接在客戶端進程使用它之前處于干凈的狀態。
mysqli擴展通過自動的調用C-API函數mysql_change_user()?來完成這個清理工作。
自動清理的特性有優點也有缺點。優點是程序員不再需要擔心附加的清理代碼，因為它們會自動調用。然而缺點就是 代碼可能會潛在的慢一點，因為每次從連接池返回一個連接都需要執行這些清理代碼。
這個自動清理的代碼可以通過在編譯php時定義MYSQLI_NO_CHANGE_USER_ON_PCONNECT?來關閉。
mysqli擴展在使用Mysql Native Driver或Mysql Client Library（libmysql）時都支持持久化連接。
MySQLi類
代表PHP和Mysql數據庫之間的一個連接。
mysqli::$affected_rows?— Gets the number of affected rows in a previous MySQL operation
mysqli::autocommit?— 打開或關閉本次數據庫連接的自動命令提交事務模式
mysqli::begin_transaction?— Starts a transaction
mysqli::change_user?— Changes the user of the specified database connection
mysqli::character_set_name?— 返回當前數據庫連接的默認字符編碼
mysqli::$client_info?— Get MySQL client info
mysqli::$client_version?— Returns the MySQL client version as a string
mysqli::close?— 關閉先前打開的數據庫連接
mysqli::commit?— 提交一個事務
mysqli::$connect_errno?— Returns the error code from last connect call
mysqli::$connect_error?— Returns a string description of the last connect error
mysqli::__construct?— Open a new connection to the MySQL server
mysqli::debug?— Performs debugging operations
mysqli::dump_debug_info?— 將調試信息輸出到日志
mysqli::errno?— 返回最近函數調用的錯誤代碼
mysqli::$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?— 對數據庫執行一次查詢
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?— 執行一個mysql查詢
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?— 回退當前事務
mysqli::rpl_query_type?— Returns RPL query type
mysqli::savepoint?— Set a named transaction savepoint
mysqli::select_db?— 選擇用于數據庫查詢的默認數據庫
mysqli::send_query?— 發送請求并返回結果
mysqli::set_charset?— 設置默認字符編碼
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::$sqlstate?— Returns the SQLSTATE error from previous MySQL operation
mysqli::ssl_set?— Used for establishing secure connections using SSL
mysqli::stat?— Gets the current system status
mysqli::stmt_init?— 初始化一條語句并返回一個用于mysqli_stmt_prepare(調用)的對象
mysqli::store_result?— Transfers a result set from the last query
mysqli::$thread_id?— Returns the thread ID for the current connection
mysqli::thread_safe?— 返回是否是線程安全的
mysqli::use_result?— Initiate a result set retrieval
mysqli::$warning_count?— Returns the number of warnings from the last query for the given link
MySQLi_STMT類
代表一個prepared語句。
mysqli_stmt::$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類
代表從一個數據庫查詢中獲取的結果集
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類
MySQLi 驅動.
client_info
客戶端API頭版本（比如：(string)”5.1.49″）
client_version
客戶端版本（比如：(int)50149）
driver_version
Mysqli驅動版本（比如：(int)101009）
embedded
是否開啟了MySQLi嵌入式支持。
reconnect
允許或阻止重連接（查看INI指令中的mysqli.reconnect）
report_mode
設置為MYSQLI_REPORT_OFF,?MYSQLI_REPORT_ALL或者?MYSQLI_REPORT_STRICT?（為錯誤拋出異常，譯注：需要和MYSQLI_REPORT_ERROR聯合使用）,?MYSQLI_REPORT_ERROR?(報告MYSQL錯誤)和?MYSQLI_REPORT_INDEX?(報告索引相關的錯誤)的任意組合。
mysqli_driver::embedded_server_end?— Stop embedded server
mysqli_driver::embedded_server_start?— Initialize and start embedded server
mysqli_driver::$report_mode?— Enables or disables internal report functions
MySQLi_Warning類
代表一個Mysql警告。
message
消息字符串
sqlstate
SQL狀態
errno
錯誤編號
mysqli_warning::__construct?— The __construct purpose
mysqli_warning::next?— The next purpose
mysqli_sql_exception類
mysqli異常處理類
mysqli_sql_exception?extends?RuntimeException?{ ????/*?屬性?*/ ????protected?string?$sqlstate?; ????/*?繼承的屬性?*/ ????protected?string?$message?; ????protected?int?$code?; ????protected?string?$file?; ????protected?int?$line?; }
別名和過時的Mysqli 函數
mysqli_bind_param?— mysqli_stmt_bind_param的別名
mysqli_bind_result?— mysqli_stmt_bind_result的別名
mysqli_client_encoding?— mysqli_character_set_name的別名
mysqli_connect?— 別名 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?— 開啟從主機讀取
mysqli_enable_rpl_parse?— 開啟RPL解析
mysqli_escape_string?— 別名 mysqli_real_escape_string
mysqli_execute?— mysqli_stmt_execute的別名
mysqli_fetch?— mysqli_stmt_fetch的別名。
mysqli_get_cache_stats?— 返回客戶端Zval緩存統計信息
mysqli_get_metadata?— mysqli_stmt_result_metadata的別名
mysqli_master_query?— 在主/從機制中強制在主機中執行一個查詢
mysqli_param_count?— mysqli_stmt_param_count的別名
mysqli_report?— 開啟或禁用（Mysql）內部（錯誤）報告函數
mysqli_rpl_parse_enabled?— 檢查是否開啟了RPL解析
mysqli_rpl_probe?— RPL探測
mysqli_send_long_data?— mysqli_stmt_send_long_data的別名
mysqli_set_opt?— mysqli_options的別名
mysqli_slave_query?— 在主/從機制中強制在從機上執行一個查詢
