The second step of preparation for PHP7 message board development

php7 tutorial column explains the second step of preparation for PHP7 message board development

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Outline of this step:
1. Super global variables$_GET $_POST
2. MYSQL database design
3. Mysqli related database operations, connection and add, delete, modify (select insert delete update) operations

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Let’s get to the point :

• 1. Super global variable $_GET $_POST
  Conceptual things are not explained here. Just like the literal meaning, get means that the user is from The form submission method is get (the attribute in the form is method="get"). If it is post, the submission method is post. The only difference is that post is safer than get and submits more content. The message board submission method must be post

// 获取姓名
$name = $_GET['name'];
$name = $_POST['name'];

// 获取联系方式
$contact= $_GET['contact'];
$contact= $_POST['contact'];

// 获取留言内容，这里如果提交的内容比较多，超过浏览器url长度限制会报错，所以还是建议用post方式
$content= $_GET['content'];
$content= $_POST['content'];

• 2. MYSQL database design

--
-- 表的结构 `feedback`
--

CREATE TABLE `feedback` (
  `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT,
  `name` varchar(100) NOT NULL COMMENT '姓名',
  `contact` varchar(100) NOT NULL COMMENT '联系方式',
  `content` text NOT NULL COMMENT '留言内容',
  `addtime` int(10) UNSIGNED NOT NULL DEFAULT '0' COMMENT '记录时间',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='留言板数据表';

Search record operation:

// localhost数据库地址，本地数据库一般都是这个或者127.0.0.1；php_course是数据表，即用户提交留言信息保存的数据表
$mysqli = mysqli_connect('localhost', '数据库账号', '数据库密码', 'php_course');
if(mysqli_connect_errno()){
    echo '连接数据库失败：'.mysqli_connect_error();
    exit;
}
mysqli_query($mysqli, "SET NAMES UTF8"); // 因为文件编码是utf8，所以数据记录集也需要设置utf8编码，否否则查询出来的结果会乱码
$sql = "SELECT * FROM feedback"; // 查询sql语句
$result = mysqli_query($mysqli, $sql); // 执行语句
$rows_num = mysqli_affected_rows($mysqli); // 返回记录数，只是一个统计，可以不用
echo $rows_num;
// 开始遍历记录集，循环获取所有feedback表中的所有记录并赋值到$all_row
$all_row = array();
while($rows = mysqli_fetch_array($result)){
    print_r($rows);
    $all_row[] = $rows;
}
// $all_row就是feedback的所有结果集
print_r($all_row);

Record storage operation:

$mysqli = mysqli_connect('localhost', 'root', '', 'php_course');
if(mysqli_connect_errno()){
    echo '连接数据库失败：'.mysqli_connect_error();
    exit;
}
mysqli_query($mysqli, "SET NAMES UTF8");
$sql = 'INSERT INTO feedback (name, contact, content, addtime) VALUES ("测试", "qq1000", "留言内容", '.$time.')';
$result = mysqli_query($mysqli, $sql);
$insert_id = mysqli_insert_id($mysqli); // 返回数据表的自增长ID，比如新用户注册返回用户ID
echo $insert_id; // 当你在调试的时候，你会发现echo是很好的帮手。
if($insert_id > 0){
    // 如果入库成功，可以做什么
}

Modification and update:

// 修改更新
// 修改之前需要根据id查找记录是否存在，如果存在则可以修改（这种情况很常用，比如用户后台，除了验证用户是否登录还需要验证当前修改的记录是否属于当前用户）
$mysqli = mysqli_connect('localhost', 'root', '', 'php_course');
if(mysqli_connect_errno()){
    echo '连接数据库失败：'.mysqli_connect_error();
    exit;
}
$sql = "SELECT * FROM feedback WHERE id = 3";
$result = mysqli_query($mysqli, $sql); // 返回一个资源标识符，通常是数字
$row = mysqli_fetch_array($result);
if(!empty($row)){
    // 执行更新操作
    $update_sql = "UPDATE feedback SET name='修改后的名字' WHERE id={$row['id']}";
    if(FALSE !== mysqli_query($mysqli, $update_sql)){
        // 修改成功
    }
}else{
    echo '信息不能再或者不属于你的。';
    exit();
}

Delete operation:

// 删除操作
// 跟修改更新同样，删除之前需要判断当前删除的记录是否存在（如果还有图片附件，需要先删除附件再删除记录）
$mysqli = mysqli_connect('localhost', 'root', '', 'php_course');
if(mysqli_connect_errno()){
    echo '连接数据库失败：'.mysqli_connect_error();
    exit;
}
$sql = "DELETE FROM feedback WHERE id = 3";
$result = mysqli_query($mysqli, $sql); // 返回一个资源标识符，通常是数字
if(FALSE !== $result){
    // 删除成功
}

This section is mainly about php mysql operations, and sql statements are relatively frequently used. , but it’s just those few syntaxes that we will commonly use in the future.

• 1. select to find records
• 2. insert into to insert data
• 3. update to modify data
• 4.delete to delete data (this It is hard deletion, which is permanent deletion and usually cannot be retrieved. There is also soft deletion, which will be discussed in the future)

Students remember to practice frequently and memorize these operations to master them. If you encounter problems during the learning process, you can discuss them at any time in the comment area below.
Okay, that’s it for this section. In the next section, we will sort out the code to make it more readable.

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