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  • PHP 笔记——操作MySQL数据库

    1. 连接MySQL服务器

    ​ mysqli_connect :此函数是该函数的别名: mysqli::__construct()

    mysqli mysqli_connect ( [string server [, string username [,
    string password [, string dbname [, int port [, string socket]]]]]] )
    
    参数 说明
    server MySQL服务器地址(host)
    username 用户名
    password 密码
    dbname 连接的数据库名称
    port MySQL服务器使用的端口号
    socket UNIX域socket
    <?php
    	$host = "127.0.0.1"; 			//MySQL服务器地址
    	$userName = "root"; 			//用户名
    	$password = "root"; 			//密码
    	if ($connID = mysqli_connect($host, $userName, $password)){
    		echo "<script type='text/javascript'>alert('数据库连接成功!');</script>";
    	}else{
    		echo "<script type='text/javascript'>alert('数据库连接失败!');</script>";
    	}
    ?>
    

    为了屏蔽由于数据库连接失败而显示的不友好的错误信息,可以在 mysqli_connect () 函数前加 “@” 来屏蔽错误提示。

    <?php
    	$host = "127.0.0.1"; 			//MySQL服务器地址
    	$userName = "root"; 			//用户名
    	$password = "111"; 				//密码
    	if ($connID = @mysqli_connect($host, $userName, $password)){
    		echo "<script type='text/javascript'>alert('数据库连接成功!');</script>";
    	}else{
    		echo "<script type='text/javascript'>alert('数据库连接失败!');</script>";
    	}
    ?>
    

    2. 选择MySQL数据库

    (1)mysqli_connect

    $connID = mysqli_connect("127.0.0.1", "root", "111", "mysql");
    

    (2)mysqli_select_db

    bool mysqli_select_db ( mysqli $link , string $dbname )
    
    参数 说明
    link 仅以过程化样式:由mysqli_connect() 或 mysqli_init() 返回的链接标识。
    dbname 数据库名称
    <?php
    	$host = "127.0.0.1"; 			//MySQL服务器地址
    	$userName = "root"; 			//用户名
    	$password = "root"; 			//密码
    	$dbName = "mysql"; 				//数据库名称
    	//建立与MySQL数据库服务器的连接,并选择数据库
    	$connID = mysqli_connect($host, $userName, $password);
    	if(mysqli_select_db($connID, $dbName)){
    		echo "数据库选择成功!";
    	}else{
    		echo "数据库选择失败!"; 
        }
    ?> 
    

    3. 执行SQL语句

    mixed mysqli_query( mysqli link, string query [, int resultmode] )
    
    参数 说明
    link 仅以过程化样式:由mysqli_connect() 或 mysqli_init() 返回的链接标识。
    query sql语句
    resultmode
    //连接MySQL服务器,选择数据库
    $conn = mysqli_connect("localhost", "root", "root", "stu") or die("连接数据库服务器失败!" . mysqli_error());
    //设置数据库编码格式utf8
    mysqli_query($conn, "set names utf8");
    
    mysqli_query($conn, "insert into users values('4', '张三', '男', '23')");
    mysqli_query($conn, "update users set  Name='张三' where Id='1'");
    mysqli_query($conn, "delete from users where Id='211789111'"); 
    mysqli_query($conn, "use stu");
    mysqli_query($conn, "set names utf8");
    $result = mysqli_query($conn, "select * from users");
    

    4. 将结果集返回到数组中

    array mysqli_fetch_array ( resource result [, int result_type] )
    
    参数 说明
    result 由 mysqli_query()函数返回的数据指针
    result_type 设置结果集数组的表达方式。
    - MYSQL_ASSOC:关联数组
    - MYSQL_NUM:数字数组
    - MYSQL_BOTH:默认。同时产生关联和数字数组。
    <?php	
    	while($myrow = mysqli_fetch_array($result)){
    ?>
    	<tr>
    		<td align="center"><span><?php echo $myrow[0]; ?></span></td>
    		<td align="center"><span><?php echo $myrow[1]; ?></span></td>
    		<td align="center"><span><?php echo $myrow[2]; ?></span></td>
    		<td align="center"><span><?php echo $myrow[3]; ?></span></td>
    	</tr>
    	<br>
    <?php
    	}
    ?> 
    

    5. 从结果集中获取一行作为对象

    mixed mysqli_fetch_object ( resource result )
    
    <?php	
    	while($myrow = mysqli_fetch_object($result)){
    ?>
    	<tr>
    		<td align="center"><span><?php echo $myrow->Id; ?></span></td>
    		<td align="center"><span><?php echo $myrow->Name; ?></span></td>
    		<td align="center"><span><?php echo $myrow->Sex; ?></span></td>
    		<td align="center"><span><?php echo $myrow->Age; ?></span></td>
    	</tr>
    	<br>
    <?php
    	}
    ?> 
    

    6. 从结果集中获取一行作为枚举数组

    mixed mysqli_fetch_row ( resource result )
    
    <?php	
    	while($myrow = mysqli_fetch_row($result)){
    ?>
    	<tr>
    		<td align="center"><span><?php echo $myrow[0]; ?></span></td>
    		<td align="center"><span><?php echo $myrow[1]; ?></span></td>
    		<td align="center"><span><?php echo $myrow[2]; ?></span></td>
    		<td align="center"><span><?php echo $myrow[3]; ?></span></td>
    	</tr>
    	<br>
    <?php
    	}
    ?> 
    

    7. 从结果集中获取一行作为关联数组

    mixed mysqli_fetch_assoc ( resource result )
    
    <?php
    	while($myrow = mysqli_fetch_assoc($result)){
    ?>
    	<tr>
    		<td align="center"><span><?php echo $myrow['Id']; ?></span></td>
    		<td align="center"><span><?php echo $myrow['Name']; ?></span></td>
    		<td align="center"><span><?php echo $myrow['Sex']; ?></span></td>
    		<td align="center"><span><?php echo $myrow['Age']; ?></span></td>
    	</tr>
    	<br>
    <?php
    	}
    ?> 
    

    8. 获取查询结果集中的记录数

    int mysqli_num_rows ( resource result )
    
    $nums = mysqli_num_rows ( $result );
    echo $nums;
    

    9. 释放内存

    void mysqli_free_result(resource result)
    

    10. 关闭连接

    bool mysqli_close ( mysqli link )
    
    mysqli_free_result($result);		// 释放内存
    mysqli_close($conn);				// 关闭连接
    

    11. 连接与关闭MySQL服务器的最佳时机

    function book_query(){
        global $conn;
        $result = mysqli_query($conn,"select * from tb_demo01");
        while($myrow = mysqli_fetch_row($result)){
            echo $myrow[1]." ";
            echo $myrow[2]."<br />";
        }
        mysqli_free_result($result);
    }
    
    $conn = mysqli_connect("localhost", "root", "111", "db_database10")
    or die("连接数据库服务器失败!".mysqli_error());
    mysqli_query($conn,"set names utf8");
    book_query();
    book_query();
    mysqli_close($conn);
    
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  • 原文地址:https://www.cnblogs.com/xzh0717/p/10661032.html
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