Head First PHP&MySQL学习笔记(2)_mysql

Head First PHP&mysql学习笔记(二)

三. 创建与填充数据库

1. Web应用是一个设计用来满足用户某个特定目标的动态网站

2. PHP代码中，SQL语句无需以分号结尾；而MySqL终端的每个SQL语句结尾都要加分号

3. 创建数据库：CREATE DATABASE database_name

    创建表：CREATE TABLE table_name(column_name1 column_type1,column_name2 column_type2,……)

    选择默认数据库：USE database_name

    展示表的结构：DESCRIBE table_name

    删除表：DROP TABLE table_name

    删除数据： DELETE FROM table_name

    新增列：ALTER TABLE table_name ADD column_name column_type

    配合where字句指定范围

4. 对于在MySQL中如何表示yes/no值可能还有异议，char(1)这种方法很直接也很高效

5. ->提示符，是标明你还在输入同一条语句，语句结束并加上分号后MySQL就会执行这条语句

6. mysqli_fetch_array()函数将一个数据行存储在一个数组中    

7. 代码示例

<?php   // addemail.php    $dbc = mysqli_connect('localhost', 'root', '', 'elvis_store')     or die('Error connecting to MySQL server.');    $first_name = $_POST['firstname'];  // 从前台获取数据   $last_name = $_POST['lastname'];   $email = $_POST['email'];    $query = "INSERT INTO email_list (first_name, last_name, email)  VALUES ('$first_name', '$last_name', '$email')";   mysqli_query($dbc, $query)          // 执行SQL语句     or die('Error querying database.');    echo 'Customer added.' . $email;    mysqli_close($dbc); ?>

</pre><pre>

<?php     // sendemail.php      $from = '[email protected]';   $subject = $_POST['subject'];   $text = $_POST['elvismail'];    $dbc = mysqli_connect('localhost', 'root', '', 'elvis_store')     or die('Error connecting to MySQL server.');    $query = "SELECT * FROM email_list";   $result = mysqli_query($dbc, $query)     or die('Error querying database.');    while ($row = mysqli_fetch_array($result)){     // while循环条件是mysqli_fetch_array()函数的返回值     $to = $row['email'];     $first_name = $row['first_name'];     $last_name = $row['last_name'];     $msg = "Dear $first_name $last_name,/n$text";     mail($to, $subject, $msg, 'From:' . $from);     echo 'Email sent to: ' . $to . '<br />';   }     mysqli_close($dbc); ?>

<?php   // removeemail.php      $dbc = mysqli_connect('localhost', 'root', '', 'elvis_store')     or die('Error connecting to MySQL server.');    $email = $_POST['email'];    $query = "DELETE FROM email_list WHERE email = '$email'";   // 删除数据库中指定条件的邮件   mysqli_query($dbc, $query)     or die('Error querying database.');    echo 'Customer removed: ' . $email;    mysqli_close($dbc); ?>

8. 主键的5大原则：主键的数据不能重复；主键必须有一个值；插入新行时必须设置主键；主键必须尽可能高效；主键值不能改变

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