How to use PHP functions for database connection and operation?

How to use PHP functions for database connection and operation?

PHP is a scripting language that is widely used in Web development and has strong capabilities in processing databases. You can use PHP functions to connect and operate with the database, and easily add, delete, modify and query data. This article will introduce how to use PHP functions for database connections and common database operations, and provide relevant code examples.

1. Database connection

First, we need to use PHP function to connect to the database. PHP provides multiple functions for different types of database connections, such as MySQL, PostgreSQL, etc. The following is an example of a database connection using MySQL:

<?php
$servername = "localhost";  // 数据库服务器名称
$username = "root";         // 数据库用户名
$password = "password";     // 数据库密码
$dbname = "myDB";           // 数据库名称

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

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

In the above example, we use the mysqli function to create a MySQL database connection. First, we need to specify parameters such as the name of the database server, user name, password, and database name. Then create a connection object through the new mysqli() function. If the connection fails, the code will provide relevant error prompts; if the connection is successful, a successful connection prompt will be output.

2. Execute database query

After connecting to the database, we can perform various operations on the database, such as insert, update, delete, etc.

1. Insert data

<?php
$sql = "INSERT INTO employees (name, age, address) 
        VALUES ('John Doe', 30, '123 Main St')";

if ($conn->query($sql) === true) {
    echo "插入数据成功";
} else {
    echo "插入数据失败: " . $conn->error;
}
?>

In the above code, we use the INSERT INTO statement to insert a piece of data into the employees table in the corresponding field. If the insertion is successful, a prompt indicating that the data was successfully inserted is output; if it fails, a failure prompt and specific error information are output.

2. Update data

<?php
$sql = "UPDATE employees 
        SET name='Jane Doe', age=28 
        WHERE id=1";

if ($conn->query($sql) === true) {
    echo "更新数据成功";
} else {
    echo "更新数据失败: " . $conn->error;
}
?>

In this example, we use the UPDATE statement to update the employees table with id 1 The recorded field value. If the update is successful, a prompt indicating that the updated data is successful will be output; if it fails, a failure prompt and specific error information will be output.

3. Delete data

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

if ($conn->query($sql) === true) {
    echo "删除数据成功";
} else {
    echo "删除数据失败: " . $conn->error;
}
?>

The above code uses the DELETE FROM statement to delete the record with id 1 from the employees table . If the deletion is successful, a prompt indicating that the data was successfully deleted is output; if it fails, a failure prompt and specific error information are output.

3. Query data

In addition to performing insert, update and delete data operations, we can also perform query operations and obtain query results.

<?php
$sql = "SELECT id, name, age, address FROM employees";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. "; Name: " . $row["name"]. "; Age: " . $row["age"]. "; Address: " . $row["address"]. "<br>";
    }
} else {
    echo "0 结果";
}
?>

In the above code, we use the SELECT statement to get all the records from the employees table. Fetch each record through the $result->fetch_assoc() function and output it to the page.

Finally, you need to remember to close the database connection:

<?php
$conn->close();
?>

The above is a simple example of using PHP functions for database connection and operation. Through the flexible use of PHP functions, we can easily interact with the database and perform various operations. I hope this article can help you understand and master PHP database operations.

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