What potential issues can arise when using PHP to compare input data with database records?

One potential issue that can arise when using PHP to compare input data with database records is the risk of SQL injection attacks if the input data is not properly sanitized. To solve this issue, it is recommended to use prepared statements with parameterized queries to prevent SQL injection attacks. 

// Using prepared statements to compare input data with database records
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username");
$stmt->bindParam(':username', $input_username);
$stmt->execute();
$result = $stmt->fetch();

if ($result) {
    // Input username matches a record in the database
    // Additional validation or actions can be performed here
} else {
    // Input username does not match any record in the database
}

Keywords

SQL injection data validation prepared statements PDO type casting

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