Getting List of Questions That Have Not Been Shown or Answered Introduction In this article, we will explore how to retrieve questions that have not been shown or answered. This involves joining two tables: Question and UserAnswerQuestion. We will also cover the SQL query required to achieve this. Background The problem at hand can be broken down into finding questions that a user has not answered yet. To do this, we need to join the Question table with the UserAnswerQuestion table based on the question_id field.

Introduction to MySQL’s Max and Distinct Record Selection with a Deleted At Column ============================================================= MySQL is an open-source relational database management system that provides various functions for data retrieval and manipulation. In this article, we will explore how to select the maximum or distinct record in MySQL using a deleted_at column, which is commonly used to track record deletion. Understanding the Problem The question at hand involves selecting distinct rows from a table where two conditions apply:

Assigning Data.table Column from Function with Column Inputs Problem Description The problem at hand revolves around creating a vectorized version of an existing R function isValidPhone, which validates phone numbers based on various parameters such as the country and state. The original implementation is not optimized for vector operations, leading to performance issues when applied to large datasets. Background Information The isValidPhone function takes several inputs, including the phone number itself, the state, the country, and a string of validation countries.

Understanding the Gap-and-Islands Problem with SQL or Spark =========================================================== The gap-and-islands problem is a classic challenge in data analysis that can be encountered while working with time-series data. The goal of this article is to explain how to solve this problem using SQL and Apache Spark, as well as provide additional insights into the underlying concepts. What is the Gap-and-Islands Problem? The gap-and-islands problem arises when dealing with time-series data that has gaps or missing values.

Plotting Different Data Frames with Custom Legends In this article, we will explore ways to plot two different data frames grouped by one or more variables, and label the legends differently. We will cover two main approaches: using different shapes for points and using different linetypes for lines. Introduction The ggplot2 library in R provides a powerful framework for creating high-quality statistical graphics. One of its key features is the ability to create automatic legends with minimal code.

Grouping Box Plot Based on Time and Coloring Based on Categories In this article, we will explore how to create a grouped box plot based on time and color them according to categories. We will also discuss the differences between using group and factor in ggplot2. Introduction Box plots are a useful visualization tool for understanding the distribution of data. They provide a quick summary of the central tendency, dispersion, and skewness of a dataset.

Introduction to sfdc Select Results in Pandas DataFrame ====================================================== As a technical blogger, I’m often asked about the intricacies of working with data from various sources, particularly when it comes to integrating Salesforce data into a pandas DataFrame. In this article, we’ll delve into the world of Salesforce data manipulation and explore how to insert the output of a query result into a pandas DataFrame. Understanding Pandas DataFrames Before diving into the specifics of working with Salesforce data in pandas, let’s take a moment to review what pandas DataFrames are and why they’re essential for data analysis.

Pandas: New value based on time interval Introduction When working with data in Pandas, it’s not uncommon to encounter situations where you need to apply conditions or rules to the data based on certain criteria. One such scenario is when you want to assign a new value to each row in a DataFrame based on a specific condition related to time intervals. In this article, we’ll explore how to achieve this using Pandas and Python.

Understanding Session Variables in PHP ===================================================== In the given Stack Overflow post, a user is experiencing an issue where a variable set by a form submission is no longer available after navigating to another form. This problem can be solved using session variables in PHP. What are Session Variables? Session variables are stored on the server-side and are used to store data that needs to be accessed across multiple pages or requests.

Working with Images in ScrollView and Photo Albums Understanding the Problem When working with UIScrollView and UIImageView in iOS development, it’s not uncommon to encounter issues when trying to save images from the scroll view. In this article, we’ll explore a common problem where an image can’t be saved to the photo album because the ScrollView object doesn’t have a property called _image. We’ll also provide solutions for saving images from the scroll view.