详解PHP中的PDO::quote(附代码实例）

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PHP在连接数据库时，可能需要为SQL语句中的字符串添加引号，为了解决这一问题，我们可以使用PHP的内置函数quote()函数，本文就带大家来看一看。

首先来看一看quote()函数的语法：

复制代码public PDO::quote    ( string $string   , int $parameter_type = PDO::PARAM_STR   ) : string1
public PDO::quote    ( string $string   , int $parameter_type = PDO::PARAM_STR   ) : string
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$string：要添加引号的字符串。
$parameter_type:为驱动提示数据类型，以便选择引号风格。
返回值:返回加引号的字符串，理论上可以安全用于 SQL 语句。如果驱动不支持这种方式，将返回 false 。

代码实例：

1.普通字符串加引号

复制代码<?php
$servername = "localhost";
$username = "root";
$password = "root123456";
$dbname   = "my_database";
 
try {
    $pdo = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    echo "连接成功"."<br>"; 
    // $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->setAttribute(PDO::ATTR_CASE, PDO::CASE_UPPER);

    $string = 'Nice';
    print "Unquoted string: $string";
    echo "<br>";
    print "Quoted string: " . $pdo->quote($string) . "n";
}catch(PDOException $e){
    echo $e->getMessage();
}1
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<?php
$servername = "localhost";
$username = "root";
$password = "root123456";
$dbname   = "my_database";
 
try {
    $pdo = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    echo "连接成功"."<br>"; 
    // $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->setAttribute(PDO::ATTR_CASE, PDO::CASE_UPPER);

    $string = 'Nice';
    print "Unquoted string: $string";
    echo "<br>";
    print "Quoted string: " . $pdo->quote($string) . "n";
}catch(PDOException $e){
    echo $e->getMessage();
}
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复制代码输出：连接成功
    Unquoted string: Nice
    Quoted string: 'Nice'1
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输出：连接成功
    Unquoted string: Nice
    Quoted string: 'Nice'
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2 危险字符串加引号

复制代码<?php
$servername = "localhost";
$username = "root";
$password = "root123456";
$dbname   = "my_database";
 
try {
    $pdo = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    echo "连接成功"."<br>"; 
    // $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->setAttribute(PDO::ATTR_CASE, PDO::CASE_UPPER);
    $string = 'Naughty ' string';
    print "Unquoted string: $string";
    echo "<br>";
    print "Quoted string:" . $pdo->quote($string);
    }1
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<?php
$servername = "localhost";
$username = "root";
$password = "root123456";
$dbname   = "my_database";
 
try {
    $pdo = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    echo "连接成功"."<br>"; 
    // $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->setAttribute(PDO::ATTR_CASE, PDO::CASE_UPPER);
    $string = 'Naughty ' string';
    print "Unquoted string: $string";
    echo "<br>";
    print "Quoted string:" . $pdo->quote($string);
    }
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复制代码输出：连接成功
Unquoted string: Naughty ' string
Quoted string:'Naughty ' string'1
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输出：连接成功
Unquoted string: Naughty ' string
Quoted string:'Naughty ' string'
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