SQL Fundamentals: Solving Real Database Queries Step by Step

In this exercise, I worked on a variety of SQL queries using both the CITY and STATION (Weather Observation Station) tables. This helped me build a strong foundation in database querying and data analysis. I began with basic queries such as retrieving all columns from the CITY table and gradually moved to more specific tasks like filtering cities based on country codes such as USA and JPN. I also learned how to extract only required fields like city names and apply conditions based on population. In addition to city-based queries, I explored weather-related datasets using the STATION table. ~ For example, I learned how to extract only American cities with populations greater than a certain threshold and how to retrieve only specific columns like city names. One interesting problem I solved involved retrieving a list of city names that do not start with vowels. To achieve this, I used multiple NOT LIKE conditions along with the DISTINCT keyword to ensure that duplicate entries were remo