一 實例化pdo對象

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

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二 數據查詢

1、如果不根據用戶傳過來的值進行操作,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));

數據是可以正常顯示的

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' =>  '大專' (length=6)'salary' =>  '5000.00' (length=7)'bonus' =>  '200.00' (length=6)'city' =>  '山東省' (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' =>  '大專' (length=6)'salary' =>  '500.00' (length=6)'bonus' =>  '200.00' (length=6)'city' =>  '陜西省' (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' =>  '大專' (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' =>  '大專' (length=6)'salary' =>  '5000.00' (length=7)'bonus' =>  '200.00' (length=6)'city' =>  '山東省' (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' =>  '大專' (length=6)'salary' =>  '500.00' (length=6)'bonus' =>  '200.00' (length=6)'city' =>  '陜西省' (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' =>  '大專' (length=6)'salary' =>  '8000.00' (length=7)...

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2、sql中帶變量進行查詢

$id = 5;
$pdo = new \PDO('mysql:host=127.0.0.1;dbname=test','root','123456');
//查詢操作
$stmt = $pdo->query("select * from user where id ='{$id}' limit 1");
$data = $stmt->fetch(2);
var_dump($data);

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3、 如果是根據用戶傳過來的值進行查詢,為了防止sql注入,就需要預處理之后再進行查詢

$dsn = "mysql:dbname=test;host=127.0.0.1";
$pdo = new PDO($dsn,'root','root');
$name = '孫娟';//這里的$name是接收用戶傳過來的值,這里我們為了簡潔,直接定位
$sql = "select * from student where name=:name";
$stmt = $pdo->prepare($sql);
$stmt->execute(array('name'=>$name));
var_dump($stmt->fetch(2));

結果同樣可以正常信息顯示:

array (size=8)'id' =>  '6' (length=1)'name' =>  '孫娟' (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' =>  '孫娟' (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)

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三 我們需要知道的連接mysql數據庫的三種方式及區別

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1、pdo

pdo操作mysql數據庫雖然效率相較于mysqli會稍微低了一點點,但勝在擴展性強,以后換數據庫可以很方便的進行遷移,代碼幾乎不用改動,所以極其推薦使用pdo連接操作數據庫

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2、mysqli

mysqli同樣可以實現連接并操作mysql數據庫,同樣和pdo一樣,也支持預處理,并且單純從效率上來說,好像還比pdo稍微好了那么一點,但缺點是它只能連接mysql數據庫,擴展性太差,一旦以后更換數據庫,很多代碼都需要重寫

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3、mysql

mysql直接連接數據庫,現在官方都把mysql函數廢棄了,你還在執著嗎? 第一它只支持mysql數據庫,可擴展性太差.第二,不支持預處理,安全問題堪憂,所以,千萬不要使用mysql連接數據庫方式,改用pdo或者mysqli吧

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想了解更多可參考?https://www.helloweba.net/php/573.html