When designing relational systems, it's crucial to know the difference between primary and related attributes. A primary attribute distinctly identifies each entry in a collection, ensuring no duplicates exist. It's similar to a identification number for each instance. In contrast, a foreign identifier creates a link between collections, referring

GROUP BY is a essential SQL clause used to summarize data based on common values. It allows you to explore your dataset by grouping rows with identical characteristics together. This technique is indispensable for extracting valuable insights from your database. Let's examine some SQL examples to illustrate how GROUP BY can be used to perform data