PHP database function realizes the function of adding, deleting, modifying and checking data

PHP database function realizes the function of adding, deleting, modifying and checking data

Abstract:
The database is an important part of storing and managing data. When developing web applications, it is often necessary to add, delete, modify, and query the database. As a popular server-side programming language, PHP provides a wealth of database functions for adding, deleting, modifying, and querying data. This article will introduce how to use PHP database functions to implement the addition, deletion, modification and query functions of data.

1. Database connection:
   Before using PHP database functions, you first need to establish a connection with the database. You can use mysqli (MySQL Improved) extension or PDO (PHP Data Objects) to connect to the database. The following is a sample code for database connection using mysqli extension:

<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "test_db";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("数据库连接失败: " . $conn->connect_error);
}
echo "数据库连接成功";
?>

2. Insertion of data:
   When using PHP database functions to insert data, you need to write a SQL insert statement first, and then execute it by This statement inserts data into the database. The following is a sample code for inserting data using the mysqli extension:

<?php
$sql = "INSERT INTO users (name, email, password) VALUES ('John', 'john@example.com', 'password123')";

// 检查插入是否成功
if ($conn->query($sql) === TRUE) {
    echo "新记录插入成功";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}
?>

3. Data query:
   When using PHP database functions to query data, you need to write a SQL query statement first, and then execute the statement to obtain data from the database. The following is a sample code for querying data using mysqli extension:

<?php
$sql = "SELECT * FROM users";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 输出每行数据
    while($row = $result->fetch_assoc()) {
        echo "姓名: " . $row["name"]. " - 邮箱: " . $row["email"]. " - 密码: " . $row["password"]. "<br>";
    }
} else {
    echo "0 结果";
}
?>

4. Data update:
   When using PHP database functions to update data, you need to write a SQL update statement first, and then execute the Statements implement data updates. The following is a sample code for updating data using mysqli extension:

<?php
$sql = "UPDATE users SET email='john.doe@example.com' WHERE id=1";

if ($conn->query($sql) === TRUE) {
    echo "记录更新成功";
} else {
    echo "Error updating record: " . $conn->error;
}
?>

5. Deletion of data:
   When using PHP database functions to delete data, you need to write a SQL delete statement first, and then execute the statement to delete data. The following is a sample code for deleting data using the mysqli extension:

<?php
$sql = "DELETE FROM users WHERE id=1";

if ($conn->query($sql) === TRUE) {
    echo "记录删除成功";
} else {
    echo "Error deleting record: " . $conn->error;
}
?>

Conclusion:
By using PHP database functions, we can easily implement the addition, deletion, modification and query functions of data. In actual project development, rational use of these functions can greatly improve development efficiency and data management flexibility. At the same time, in order to ensure the security of database operations, we also need to pay attention to effective filtering of user input and measures to prevent SQL injection attacks.

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