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'];
$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)
or die('Error querying database.');

echo 'Customer added.' . $email;

mysqli_close($dbc);
?>

<?php
// sendemail.php

$from = 'elmer@makemeelvis.com';
$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)){
$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'";
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