What potential pitfalls should PHP developers be aware of when executing database queries that involve both updates and reads?

When executing database queries that involve both updates and reads, PHP developers should be aware of the risk of data inconsistency due to concurrent access. To prevent this, developers can use transactions to ensure that updates and reads are executed atomically, maintaining data integrity. 

// Start a transaction
$pdo->beginTransaction();

try {
    // Execute update query
    $stmt = $pdo->prepare("UPDATE table SET column = :value WHERE id = :id");
    $stmt->execute(['value' => $newValue, 'id' => $id]);

    // Execute read query
    $stmt = $pdo->prepare("SELECT * FROM table WHERE id = :id");
    $stmt->execute(['id' => $id]);

    // Commit the transaction
    $pdo->commit();
} catch (Exception $e) {
    // Rollback the transaction in case of an error
    $pdo->rollBack();
    echo "Error: " . $e->getMessage();
}

Keywords

SQL injection transaction management concurrency issues database locks query optimization

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