DELIMITER ;; /*!50003 CREATE*/ /*!50017 DEFINER=`root`@`localhost`*/ CREATE TRIGGER `copies BEFORE INSERT ON `copies` FOR EACH ROW BEGIN DECLARE v_title VARCHAR(254); DECLARE v_BorD INT; SET v_BorD = (SELECT copies.artNr FROM copies WHERE barcode = NEW.barcode AND title IS NULL); IF(v_BorD > 0) THEN SET NEW.title = (SELECT bTitle FROM books JOIN copies ON books.isbn=copies.isbn WHERE copies.barcode=NEW.barcode); END IF; END */;; DELIMITER ; Explanation: The issue is that the triggers are being applied before the data is inserted or updated, and since title doesn’t exist yet in the table being triggered on (copies), it throws an error.

Understanding Shadows in iOS Creating a shadow effect on an iPhone’s screen can be achieved using the CAShadow class, which is part of the Core Animation framework. This tutorial will delve into the world of shadows and provide a step-by-step guide on how to create a top-half red shadow for a specific layer. What are Shadows in iOS? A shadow is a graphical effect that creates a visual representation of an object casting a shadow when it’s placed against another object or surface.

Understanding Rare Errors in R: A Deep Dive into Model Fitting and Prediction Introduction As a developer, we’ve all encountered those frustrating errors that make us scratch our heads and wonder how we’ll ever debug them. In this article, we’ll delve into the world of rare errors in R, specifically focusing on model fitting and prediction. We’ll explore what causes these issues, how to identify them, and most importantly, how to fix them.

Understanding WebView Interaction with View Controller As a developer working on an iOS application, you may encounter scenarios where you need to interact with your UIWebView instances from other parts of your codebase. In this article, we will explore how to achieve this interaction and address the specific issue mentioned in the Stack Overflow post. Background and Terminology To begin with, let’s clarify some terms: View Controller: A class that manages a view hierarchy for an iOS application.

Understanding the Error: A Deep Dive into Data Manipulation and Formulae in R R is a popular programming language for statistical computing and is widely used in various fields, including data science, research, and business. One of the key features of R is its ability to manipulate and transform data using data manipulation languages such as dplyr, tidyr, and reshape2. In this article, we will delve into a common error that occurs when working with these languages and explore how to resolve it.

Working with CSV Files and Different Separators in Pandas When working with CSV files, it’s common to encounter different separators, such as tab (\t) or semi-colon (;). In this article, we’ll explore how to write a function to read CSV files with different separators in pandas using Python. Understanding the Problem We have a bunch of CSV files for different years named my_file_2019, my_file_2020, my_file_2023 and so on. Some files have tab separator while others have semi-colon.

Introduction to Consumable In-App Purchases and Backup/Restore Process As a developer, it’s essential to understand how to handle in-app purchases (IAP) in your app. One type of IAP is consumable, which allows users to purchase items that can be used up over time. In this article, we’ll explore the process of backing up and restoring consumable in-app purchases tracked in NSUserDefaults to/from iCloud or Dropbox. What are Consumable In-App Purchases? Consumable IAPs allow users to purchase items that can be used up over time.

SQL Logic to Fail a Check if Any of the Related Customers Have Failed Introduction As data management becomes increasingly complex, it’s essential to develop efficient and effective ways to analyze and process large datasets. One common challenge in data analysis is handling relationships between different tables or datasets. In this article, we’ll explore how to use SQL logic to fail a check if any of the related customers have failed.

Working with Pandas DataFrames: Flipping on a Column and Creating a Dictionary Introduction to Pandas and DataFrames Pandas is a powerful Python library used for data manipulation and analysis. It provides high-performance, easy-to-use data structures like Series (1-dimensional labeled array) and DataFrame (2-dimensional labeled data structure with columns of potentially different types). In this article, we’ll explore how to work with Pandas DataFrames, specifically on how to flip a column and create a dictionary from it.

Understanding UISearchBar and Its Life Cycle As developers, we often face challenges when implementing search functionality in our apps. In this article, we will delve into the life cycle of UISearchBar and explore how to overcome a common issue where the results are not displayed until the “Cancel” button is clicked. Introduction to UISearchController and SearchBar UISearchController and UISearchBar are two essential components in iOS development that work together to provide a seamless search experience.