Diademata

Your company hired an intern database engineer, who immediately started updating the data in the system. Unfortunately, he hasn't fully grasped the concept of NULL values yet and he performed some incorrect inserts and updates to the departments table, which has the following structure: id: the unique department ID; name: the name of the department; description: the description of the department..

Implement the missing code, denoted by ellipses. You may not modify the pre-existing code.You've been dreaming about becoming a famous hacker all your life, and now it's time to make your dreams come true! You decided to start by finding a website that has some vulnerability, and you just found a doozy. This particular website has an open database users that contains information about the people..

Your company is planning to expand internationally very soon. You have been tasked with preparing a report on foreign markets and potential competitors. After some investigation, you've created a database containing a foreignCompetitors table, which has the following structure: competitor: the name of the competitor;country: the country in which the competitor is operating.In your report, you ne..

You have a table soccer_team that contains information about the players in your favorite soccer team. This table has the following structure: id: the unique ID of the player;first_name: the first name of the player;surname: the last name of the player;player_number: the number that the player wears (the number is guaranteed to be unique).Create a semicolon-separated list of all the players, sor..

You are an avid traveler and you've visited so many countries that when people ask you where you've been, you can't even remember all of them! Luckily, every time you travel somewhere you write down the trip information in your diary. Now you want to get a list of all the different countries that you have visited using the information in your diary. The diary is represented as a table diary, whi..

You want to expand your movie collection, but you don't really have any preferences so you're not sure where to start. After some consideration, you decide that you should start by finding more movies from award-winning directors whose movies you already own and who have shot a movie somewhat recently. To find the directors whose movies you might want to consider watching in the first place, you..

You are curious about the geographical distribution of CodeSignal users, so you have created a list of countries along with the number of registered users from each. Your task now is to calculate the number of users on each continent. The information about the countries is stored in a table countries, which has 3 columns: country: the name of the country;continent: the name of the continent wher..

You recently started working in the IT department of a large store. You were put in charge of the inventory database availableItems, which has the following structure: id: unique item ID;item_name: the name of the item;item_type: the type of the item.Note that it is possible for items that are of different types to have the same names. One of the most common operations performed on this database..

Your friend wants to become a professional tour guide and travel all around the world. In pursuit of this dream, she enrolled in tour guide school. The professors in this school turned out to be very demanding, and one of them gave your friend a difficult assignment that she has to finish over the weekend. Here's the task: Given a list of countries, your friend should calculate the average popul..

You are managing a small newspaper subscription service. Anyone who uses it can subscribe to a large number of different newspapers for a full year or just a half year. The information about subscriptions is stored in the full_year and half_year tables, which have the following structures: full_year:id: the unique subscription ID;newspaper: the newspaper's name;subscriber: the name of the subscr..