> For the complete documentation index, see [llms.txt](https://everythingblackkk.gitbook.io/everythingblackkk/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://everythingblackkk.gitbook.io/everythingblackkk/php-security/sql-injection-php.md).

# SQL injection (PHP)

***

### PHP code vulnerable to SQL injection.

```php
<?php
    include "conect.php";

    $id = $_GET['input'];

    $qy = $con->prepare("SELECT username, email FROM users WHERE id=$id");

    $qy->execute();
    $users = $qy->fetch();
    $count = $qy->rowCount();
    
    echo "email is : " . $users['email'] . "<br>";
    echo "username is : " . $users['username'];

?>
```

***

### Secure PHP Code Explanation

```php
$qy = $con->prepare("SELECT username, email FROM users WHERE id=$id");
```

In this code, there was a problem: we were taking the `id` directly from the **GET request** without any validation. The issue here is that any user could inject a malicious SQL query and even **drop the entire database** easily.

To solve this, we need to use **prepared statements**.

```php
$qy = $con->prepare("SELECT username, email FROM users WHERE id = ?");
```

The `?` is a **parameter placeholder** in prepared statements. It's a fundamental security feature that prevents SQL injection.

#### What the `?` does:

The `?` creates a **placeholder** for data that will be supplied later, keeping the SQL structure separate from the actual values.

The second problem in the code was that there was **no check to ensure** the user actually provides a value in `$_GET['input']`. This could cause **unexpected errors** that should be handled properly instead of being displayed to the user.

The third thing we need to ensure is that the **ID actually exists** in the database. We can check this using `$count = $qy->rowCount();`, which returns the number of rows from our query. If no rows are returned, that means no result exists — so instead of showing an error, we can display a friendly message like “User not found”.

> Additional Security Improvements: We Can Use `htmlspecialchars()` Fucntion when outputting data to prevent XSS attacks I Talk About It In This Video => <https://www.youtube.com/watch?v=1gbaS6uZ-d8>

***

#### Secure Code:

```php
<?php
include "conect.php";

if (isset($_GET['input']) || !empty($_GET['input'])) {

    $id = $_GET['input'];

    $qy = $con->prepare("SELECT username, email FROM users WHERE id = ?");
    $qy->execute([$id]);

    $users = $qy->fetch();
    $count = $qy->rowCount();

    if ($count > 0) {
        echo "email is : " . htmlspecialchars($users['email']);
        echo "<br>";
        echo "username is : " . htmlspecialchars($users['username']);
    } else {
        echo "User not found";
    }

} else {
    echo "[!] Missing 'input' Parameter In URL";
}
?>
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://everythingblackkk.gitbook.io/everythingblackkk/php-security/sql-injection-php.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.