php分享十五:php的数据库操作

一:术语解释:

What is an Extension?

API和扩展不能理解为一个东西,因为扩展不一定暴露一个api给用户

The PDO MySQL driver extension, for example, does not expose an API to the PHP programmer, but provides an interface to the PDO layer above it.

The terms API and extension should not be taken to mean the same thing, as an extension may not necessarily expose an API to the programmer.

参考:http://php.net/manual/zh/mysqlinfo.terminology.php

二:扩展选择:

ext/mysqli PDO_MySQL ext/mysql
PHP version introduced 5.0 5.1 2.0
Included with PHP 5.x Yes Yes Yes
Included with PHP 7.x Yes Yes No
Development status Active Active Maintenance only in 5.x; removed in 7.x
Lifecycle Active Active Deprecated in 5.x; removed in 7.x
Recommended for new projects Yes Yes No
OOP Interface Yes Yes No
Procedural Interface Yes No Yes
API supports non-blocking, asynchronous queries with mysqlnd Yes No No
Persistent Connections Yes Yes Yes
API supports Charsets Yes Yes Yes
API supports server-side Prepared Statements Yes Yes No
API supports client-side Prepared Statements No Yes No
API supports Stored Procedures Yes Yes No
API supports Multiple Statements Yes Most No
API supports Transactions Yes Yes No
Transactions can be controlled with SQL Yes Yes Yes
Supports all MySQL 5.1+ functionality Yes Most No

三:选择mysql驱动(Choosing a library)

mysqli,mysql,pdo底层都是用c写的,有两种底层c库可以使用(mysqlnd library 和 libmysqlclient library),通过编译参数可以更改区别:

mysqlnd更胜一筹;

从php5.3开始,mysqlnd成为php的一部分发布,mysqlnd提供的高级功能有:lazy connections and query caching (这两个功能libmysqlclient library是没有的)

编译配置:

// Recommended, compiles with mysqlnd
$ ./configure --with-mysqli=mysqlnd --with-pdo-mysql=mysqlnd --with-mysql=mysqlnd // Alternatively recommended, compiles with mysqlnd as of PHP 5.4
$ ./configure --with-mysqli --with-pdo-mysql --with-mysql // Not recommended, compiles with libmysqlclient
$ ./configure --with-mysqli=/path/to/mysql_config --with-pdo-mysql=/path/to/mysql_config --with-mysql=/path/to/mysql_config 注意:可以分别指定mysqli, mysql, pdo 扩展的底层c库
  MySQL native driver (mysqlnd) MySQL client server library (libmysqlclient)
Part of the PHP distribution Yes No
PHP version introduced 5.3.0 N/A
License PHP License 3.01 Dual-License
Development status Active Active
Lifecycle No end announced No end announced
PHP 5.4 and above; compile default (for all MySQL extensions) Yes No
PHP 5.3; compile default (for all MySQL extensions) No Yes
Compression protocol support Yes (5.3.1+) Yes
SSL support Yes (5.3.3+) Yes
Named pipe support Yes (5.3.4+) Yes
Non-blocking, asynchronous queries Yes No
Performance statistics Yes No
LOAD LOCAL INFILE respects the open_basedir directive Yes No
Uses PHP's native memory management system (e.g., follows PHP memory limits) Yes No
Return numeric column as double (COM_QUERY) Yes No
Return numeric column as string (COM_QUERY) Yes Yes
Plugin API Yes Limited
Read/Write splitting for MySQL Replication Yes, with plugin No
Load Balancing Yes, with plugin No
Fail over Yes, with plugin No
Lazy connections Yes, with plugin No
Query caching Yes, with plugin No
Transparent query manipulations (E.g., auto-EXPLAIN or monitoring) Yes, with plugin No

  MySQL native driver (mysqlnd) MySQL client server library (libmysqlclient)
Part of the PHP distribution Yes No
PHP version introduced 5.3.0 N/A
License PHP License 3.01 Dual-License
Development status Active Active
Lifecycle No end announced No end announced
PHP 5.4 and above; compile default (for all MySQL extensions) Yes No
PHP 5.3; compile default (for all MySQL extensions) No Yes
Compression protocol support Yes (5.3.1+) Yes
SSL support Yes (5.3.3+) Yes
Named pipe support Yes (5.3.4+) Yes
Non-blocking, asynchronous queries Yes No
Performance statistics Yes No
LOAD LOCAL INFILE respects the open_basedir directive Yes No
Uses PHP's native memory management system (e.g., follows PHP memory limits) Yes No
Return numeric column as double (COM_QUERY) Yes No
Return numeric column as string (COM_QUERY) Yes Yes
Plugin API Yes Limited
Read/Write splitting for MySQL Replication Yes, with plugin No
Load Balancing Yes, with plugin No
Fail over Yes, with plugin No
Lazy connections Yes, with plugin No
Query caching Yes, with plugin No
Transparent query manipulations (E.g., auto-EXPLAIN or monitoring)

四:mysql字符集设置

字符设置必须用特定的函数来设置,而不能用query来处理

<?php

$mysqli = new mysqli("localhost", "my_user", "my_password", "world");

// Will NOT affect $mysqli->real_escape_string();
$mysqli->query("SET NAMES utf8");

// Will NOT affect $mysqli->real_escape_string();
$mysqli->query("SET CHARACTER SET utf8");

// But, this will affect $mysqli->real_escape_string();
$mysqli->set_charset('utf8');

// But, this will NOT affect it (utf-8 vs utf8) -- don't use dashes here
$mysqli->set_charset('utf-8');

?>

注意:

设置utf8编码时,不能用utf-8,而是utf8(因为在mysql中设置编码不能包含-)

NotePossible UTF-8 confusion

Because character set names in MySQL do not contain dashes, the string "utf8" is valid in MySQL to set the character set to UTF-8. The string "utf-8" is not valid, as using "utf-8" will fail to change the character set.

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