Head First PHP&MySQL study notes (2)

3. Create and populate the database

1. A web application is a dynamic website designed to meet a specific goal of the user

2. In PHP code, SQL statements do not need to end with a semicolon; while MySqL A semicolon must be added to the end of each SQL statement in the terminal

3. Create a database: CREATE DATABASE database_name

Create a table: CREATE TABLE table_name(column_name1 column_type1,column_name2 column_type2,…)

Select default database: USE database_name

Show the structure of the table: DESCRIBE table_name

Delete table: DROP TABLE table_name

Delete data: DELETE FROM table_name

Use the where clause to specify the range

4. There may be objections to how to express yes/no values ​​in MySQL. The char(1) method is very straightforward. Very efficient

5. The -> prompt indicates that you are still entering the same statement. After the statement ends and a semicolon is added, MySQL will execute the statement

6. The mysqli_fetch_array() function stores a data row in an array

7. Code example

<?php
  // addemail.php

  $dbc = mysqli_connect(&#39;localhost&#39;, &#39;root&#39;, &#39;&#39;, &#39;elvis_store&#39;)
    or die(&#39;Error connecting to MySQL server.&#39;);

  $first_name = $_POST[&#39;firstname&#39;];  // 从前台获取数据
  $last_name = $_POST[&#39;lastname&#39;];
  $email = $_POST[&#39;email&#39;];

  $query = "INSERT INTO email_list (first_name, last_name, email)  VALUES (&#39;$first_name&#39;, &#39;$last_name&#39;, &#39;$email&#39;)";
  mysqli_query($dbc, $query)          // 执行SQL语句
    or die(&#39;Error querying database.&#39;);

  echo &#39;Customer added.&#39; . $email;

  mysqli_close($dbc);
?>

<pre name="code" class="php"><?php
&#160;&#160;// sendemail.php

  $from = 'jarray@foxmail.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)            // 执行SQL语句
    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);
&#160; &#160; echo &#39;Email sent to: &#39; . $to . &#39;<br />';
  } 

  mysqli_close($dbc);
?>

<?php
  // removeemail.php
&#160; 
&#160; $dbc = mysqli_connect(&#39;localhost&#39;, &#39;root&#39;, &#39;&#39;, &#39;elvis_store&#39;)
    or die(&#39;Error connecting to MySQL server.&#39;);

  $email = $_POST[&#39;email&#39;];

  $query = "DELETE FROM email_list WHERE email = &#39;$email&#39;";   // 删除数据库中指定条件的邮件
  mysqli_query($dbc, $query)
    or die(&#39;Error querying database.&#39;);

  echo &#39;Customer removed: &#39; . $email;

  mysqli_close($dbc);
?>

The above introduces the Head First PHP&MySQL study notes (2), including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.