How to access database database database in html

How HTML accesses the database

In today's digital era, we need to communicate data through the Internet. In order to realize this function, we need to use two key technologies: HTML and database. HTML (Hypertext Markup Language) is a standard format for describing web content, while a database is a software application used to store and manage data. In this article, we will discuss how to access the database through HTML.

HTML is often considered a static technology because it can only display pre-designed content. To get more interactivity, we need to use dynamic techniques. In these technologies, HTML is used as the front end, while the back end is some programming language and database. In this case, we need to use server-side scripting language to connect to the database to query and modify data. Below we will introduce how to access the database through HTML from two aspects.

Use PHP and MySQL to access the database

PHP is a server-side scripting language, while MySQL is a widely used open source database management system. Using these two technologies, we can easily access and modify the database. Here are some steps showing how to use PHP and MySQL to connect to the database, send query statements, and get results:

1. First, you need to install PHP on your local server. You can download PHP from the official website and follow the prompts to install it.

2. Next, you need to connect to the MySQL database. You can download MySQL from the MySQL official website and install it.

3. Use the following code in PHP to connect to MySQL:

$servername = "localhost";
$username = "root";
$password = "" ;
//Create connection
$conn = new mysqli($servername, $username, $password);
//Detect connection
if ($conn->connect_error) {

die("Connection failed: " . $conn->connect_error);

}
echo "Connected successfully";

4. Create a new database and table:

$sql = "CREATE DATABASE myDB";
if ( $conn->query($sql) === TRUE) {

echo "Database created successfully";

} else {

echo "Error creating database: " . $conn->error;

}

$sql = "CREATE TABLE MyGuests (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP
)";
if ($conn->query($sql) === TRUE) {

echo "Table MyGuests created successfully";

} else {

echo "Error creating table: " . $conn->error;

}

5. Now, use the following code in PHP to query the table:

$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = $conn->query($sql);
if ($result->num_rows > 0) {

// 输出每行数据
while($row = $result->fetch_assoc()) {
    echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
}

} else {

echo "0 results";

}

The following are some information about accessing databases using PHP and MySQL The basics, however, this article does not cover everything in depth.

Use Javascript and Firebase to access the database

Firebase is a real-time database that is a cloud-based solution provided by Google. Here are some steps on how to connect to a real-time database and get data using JavaScript and Firebase:

1. First, you need to create a new project on Firebase and generate a key for your application. By adding this key to your JavaScript file, you allow your application to connect to Firebase.

2. Now, you need to connect to the Firebase database from JavaScript using the following code:

var config = {

apiKey: "YOUR_API_KEY",
authDomain: "YOUR_AUTH_DOMAIN",
databaseURL: "YOUR_DATABASE_URL",
storageBucket: "YOUR_STORAGE_BUCKET",

};
firebase.initializeApp(config) ;

3. Use the following code to query data:

var firebaseRef = firebase.database().ref("users/");
firebaseRef.once("value") .then(function(snapshot) {

snapshot.forEach(function(childSnapshot) {
    var childKey = childSnapshot.key;
    var childData = childSnapshot.val();
    console.log("Child key: " + childKey + ", Child value: " + childData);
});

});

The above code will query the data set named "users" in Firebase and print the key and value of each child element into the browser console.

Conclusion

HTML and database technologies are at the core of modern web applications. Although HTML technology is mainly responsible for the front-end, we need to use back-end technology to implement functions such as database access. In this article, we show you how to connect to the database and retrieve data using two technologies: PHP and MySQL, Javascript and Firebase. This code is just a starting point, but clearly highlights the key points of using HTML to access a database.

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