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PHP连接MYSQL数据库

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叫我可儿呀

修改于 2019-12-05 10:17:03

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代码可运行

文章被收录于专栏：前端,Java专栏前端,Java专栏

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代码可运行

连接MYSQL

面向对象风格

<?php  
$mysqli  = new  mysqli ( 'localhost' ,  'my_user' ,  'my_password' ,  'my_db' );  
  
/*  
 * This is the "official" OO way to do it,  
 * BUT $connect_error was broken until PHP 5.2.9 and 5.3.0.  
 */  
if ( $mysqli -> connect_error ) {  
    die( 'Connect Error ('  .  $mysqli -> connect_errno  .  ') '  
             .  $mysqli -> connect_error );  
}  
  
/*  
 * Use this instead of $connect_error if you need to ensure  
 * compatibility with PHP versions prior to 5.2.9 and 5.3.0.  
 */  
if ( mysqli_connect_error ()) {  
    die( 'Connect Error ('  .  mysqli_connect_errno () .  ') '  
             .  mysqli_connect_error ());  
}  
  
echo  'Success... '  .  $mysqli -> host_info  .  "\n" ;  
  
$mysqli -> close ();  
?>

面向对象风格 when extending mysqli class

<?php  
  
class  foo_mysqli  extends  mysqli  {  
    public function  __construct ( $host ,  $user ,  $pass ,  $db ) {  
         parent :: __construct ( $host ,  $user ,  $pass ,  $db );  
  
        if ( mysqli_connect_error ()) {  
            die( 'Connect Error ('  .  mysqli_connect_errno () .  ') '  
                     .  mysqli_connect_error ());  
        }  
    }  
}  
  
$db  = new  foo_mysqli ( 'localhost' ,  'my_user' ,  'my_password' ,  'my_db' );  
  
echo  'Success... '  .  $db -> host_info  .  "\n" ;  
  
$db -> close ();  
?>

过程化风格

<?php  
$link  =  mysqli_connect ( 'localhost' ,  'my_user' ,  'my_password' ,  'my_db' );  //连接数据库
  
if (! $link ) {  
    die( 'Connect Error ('  .  mysqli_connect_errno () .  ') '  
             .  mysqli_connect_error ());  
}  
  
echo  'Success... '  .  mysqli_get_host_info ( $link ) .  "\n" ;  
  
mysqli_close ( $link );  //关闭数据库连接
?>

执行SQL语句使用 mysql_query() 函数。此函数用于向 MySQL 连接发送查询或命令例子在下面的例子中，我们创建了一个名为 "my_db" 的数据库：

<?php
$con = mysqli_connect("localhost","peter","abc123");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

if (mysql_query("CREATE DATABASE my_db",$con))
  {
  echo "Database created";
  }
else
  {
  echo "Error creating database: " . mysql_error();
  }

mysqli_close($con);
?>

向数据库表插入数据

<?php
$con = mysql_connect("localhost","peter","abc123");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

mysql_select_db("my_db", $con);    //选择数据库

mysql_query("INSERT INTO Persons (FirstName, LastName, Age) 
VALUES ('Peter', 'Griffin', '35')");

mysql_query("INSERT INTO Persons (FirstName, LastName, Age) 
VALUES ('Glenn', 'Quagmire', '33')");

mysqli_close($con);
?>
把来自表单的数据插入数据库
现在，我们创建一个 HTML 表单，这个表单可把新记录插入 "Persons" 表。
这是这个 HTML 表单：
<html>
<body>

<form action="insert.php" method="post">
Firstname: <input type="text" name="firstname" />
Lastname: <input type="text" name="lastname" />
Age: <input type="text" name="age" />
<input type="submit" />
</form>

</body>
</html>

当用户点击上例中 HTML 表单中的提交按钮时，表单数据被发送到 "insert.php"。"insert.php" 文件连接数据库，并通过 $_POST 变量从表单取回值。然后，mysql_query() 函数执行 INSERT INTO 语句，一条新的记录会添加到数据库表中。下面是 "insert.php" 页面的代码：

<?php
$con = mysqli_connect("localhost","peter","abc123");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

mysql_select_db("my_db", $con); //选择数据库

$sql="INSERT INTO Persons (FirstName, LastName, Age)
VALUES
('$_POST[firstname]','$_POST[lastname]','$_POST[age]')";

if (!mysql_query($sql,$con))
  {
  die('Error: ' . mysql_error());
  }
echo "1 record added";

mysqli_close($con)
?>