How to use PHP to implement data addition, deletion, modification and query functions in MySQL

How to use PHP to implement data addition, deletion, modification and query functions in MySQL

Summary
MySQL is an open source relational database management system, and PHP is A popular server-side scripting language. Combining MySQL and PHP, we can easily implement the addition, deletion, modification and query functions of the database. This article will introduce you to how to use PHP to implement these functions in MySQL and provide specific code examples.

1. Connect to MySQL database
   First, we need to connect to the MySQL database using PHP. We can use the mysqli_connect() function in PHP to connect by providing the hostname, username, password and database name.

$host = "localhost";
$username = "root";
$password = "password";
$database = "mydatabase";

$conn = mysqli_connect($host, $username, $password, $database);
if (!$conn) {
    die("连接数据库失败：" . mysqli_connect_error());
}

2. Insert data
   Next, we will demonstrate how to insert data in the MySQL database. Use the mysqli_query() function to execute the INSERT INTO statement to insert new records into the specified table.

$name = "John Doe";
$email = "johndoe@example.com";
$phone = "1234567890";

$sql = "INSERT INTO users (name, email, phone) VALUES ('$name', '$email', '$phone')";
if (mysqli_query($conn, $sql)) {
    echo "成功插入数据";
} else {
    echo "插入数据失败：" . mysqli_error($conn);
}

3. Querying Data
   Now, we will show how to query data in a MySQL database. Using the mysqli_query() and mysqli_fetch_assoc() functions, we can execute a SELECT statement and iterate through the query results.

$sql = "SELECT * FROM users";
$result = mysqli_query($conn, $sql);

if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "姓名：" . $row['name'] . "，邮箱：" . $row['email'] . "，电话：" . $row['phone'] . "<br>";
    }
} else {
    echo "没有数据";
}

4. Update data
   If we need to update existing data, we can use the UPDATE statement and WHERE condition to perform the update operation.

$id = 1;
$newPhone = "9876543210";

$sql = "UPDATE users SET phone='$newPhone' WHERE id=$id";
if (mysqli_query($conn, $sql)) {
    echo "成功更新数据";
} else {
    echo "更新数据失败：" . mysqli_error($conn);
}

5. Deleting Data
   Finally, we will demonstrate how to delete data from a MySQL database. Using the DELETE FROM statement and WHERE condition, we can delete records that meet the specified conditions.

$id = 1;

$sql = "DELETE FROM users WHERE id=$id";
if (mysqli_query($conn, $sql)) {
    echo "成功删除数据";
} else {
    echo "删除数据失败：" . mysqli_error($conn);
}

Summary
With the powerful functions of MySQL and PHP, we can easily implement addition, deletion, modification and query operations of the database. By connecting to the MySQL database and performing insert, query, update, and delete operations, we can effectively manage and manipulate data. This article provides specific code examples to help you understand and apply these features. Please remember that operations on the database need to be handled with caution to ensure data security and integrity.

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