pdo连接mysql数据库(简洁明了)

发布时间：2024-11-29 19:44

理解数据库原理（SQL、MySQL） #生活知识# #编程教程#

一实例化pdo对象

$dsn = "mysql:dbname=test;host=127.0.0.1";

$pdo = new PDO($dsn,'root','root');

二数据查询

1、如果不根据用户传过来的值进行操作,可以直接query sql

$dsn = "mysql:dbname=test;host=127.0.0.1";

$pdo = new PDO($dsn,'root','root');

$sql = "select * from student";

$stmt = $pdo->query($sql);

var_dump($stmt->fetchAll(2));

数据是可以正常显示的

array (size=39)

0 =>

array (size=8)

'id' => '1' (length=1)

'name' => '周更生' (length=9)

'sex' => '男' (length=3)

'age' => '24' (length=2)

'edu' => '大专' (length=6)

'salary' => '5000.00' (length=7)

'bonus' => '200.00' (length=6)

'city' => '山东省' (length=9)

1 =>

array (size=8)

'id' => '2' (length=1)

'name' => '王小平' (length=9)

'sex' => '男' (length=3)

'age' => '28' (length=2)

'edu' => '大专' (length=6)

'salary' => '500.00' (length=6)

'bonus' => '200.00' (length=6)

'city' => '陕西省' (length=9)

2 =>

array (size=8)

'id' => '3' (length=1)

'name' => '周改娟' (length=9)

'sex' => '女' (length=3)

'age' => '28' (length=2)

'edu' => '大专' (length=6)

'salary' => '8000.00' (length=7)...

(size=39) 0 => array (size=8) 'id' => '1' (length=1) 'name' => '周更生' (length=9) 'sex' => '男' (length=3) 'age' => '24' (length=2) 'edu' => '大专' (length=6) 'salary' => '5000.00' (length=7) 'bonus' => '200.00' (length=6) 'city' => '山东省' (length=9) 1 => array (size=8) 'id' => '2' (length=1) 'name' => '王小平' (length=9) 'sex' => '男' (length=3) 'age' => '28' (length=2) 'edu' => '大专' (length=6) 'salary' => '500.00' (length=6) 'bonus' => '200.00' (length=6) 'city' => '陕西省' (length=9) 2 => array (size=8) 'id' => '3' (length=1) 'name' => '周改娟' (length=9) 'sex' => '女' (length=3) 'age' => '28' (length=2) 'edu' => '大专' (length=6) 'salary' => '8000.00' (length=7)...

2、sql中带变量进行查询

$id = 5;

$pdo = new \PDO('mysql:host=127.0.0.1;dbname=test','root','123456');

$stmt = $pdo->query("select * from user where id ='{$id}' limit 1");

$data = $stmt->fetch(2);

var_dump($data);

3、如果是根据用户传过来的值进行查询,为了防止sql注入,就需要预处理之后再进行查询

$dsn = "mysql:dbname=test;host=127.0.0.1";

$pdo = new PDO($dsn,'root','root');

$name = '孙娟';

$sql = "select * from student where name=:name";

$stmt = $pdo->prepare($sql);

$stmt->execute(array('name'=>$name));

var_dump($stmt->fetch(2));

结果同样可以正常信息显示:

array (size=8)

'id' => '6' (length=1)

'name' => '孙娟' (length=6)

'sex' => '女' (length=3)

'age' => '24' (length=2)

'edu' => '大本' (length=6)

'salary' => '12300.00' (length=8)

'bonus' => '1080.00' (length=7)

'city' => '北京市' (length=9)

(size=8) 'id' => '6' (length=1) 'name' => '孙娟' (length=6) 'sex' => '女' (length=3) 'age' => '24' (length=2) 'edu' => '大本' (length=6) 'salary' => '12300.00' (length=8) 'bonus' => '1080.00' (length=7) 'city' => '北京市' (length=9) 三我们需要知道的连接mysql数据库的三种方式及区别

1、pdo

pdo操作mysql数据库虽然效率相较于mysqli会稍微低了一点点,但胜在扩展性强,以后换数据库可以很方便的进行迁移,代码几乎不用改动,所以极其推荐使用pdo连接操作数据库

2、mysqli

mysqli同样可以实现连接并操作mysql数据库,同样和pdo一样,也支持预处理,并且单纯从效率上来说,好像还比pdo稍微好了那么一点,但缺点是它只能连接mysql数据库,扩展性太差,一旦以后更换数据库,很多代码都需要重写

3、mysql

mysql直接连接数据库,现在官方都把mysql函数废弃了,你还在执着吗? 第一它只支持mysql数据库,可扩展性太差.第二,不支持预处理,安全问题堪忧,所以,千万不要使用mysql连接数据库方式,改用pdo或者mysqli吧

想了解更多可参考 https://www.helloweba.net/php/573.html

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