Name

Country

Gender

CustomerID

Removing duplicate entries and standardizing data formats

Extracting data from multiple operational databases

Creating surrogate keys for dimension tables

Loading data into the data warehouse

Aggregated Fact Table

Star Schema

Detailed Fact Table

Dimension Table

Contains non-numeric attributes describing entities

Stores business transactions or measurements, typically numeric

Contains surrogate keys for all dimensions

Stores summarized data about various dimensions

SELECT RestaurantName, DishName FROM Dishes RIGHT JOIN Restaurants ON Dishes.RestaurantID = Restaurants.RestaurantID;

SELECT RestaurantName, DishName FROM Dishes FULL JOIN Restaurants ON Dishes.RestaurantID = Restaurants.RestaurantID;

SELECT RestaurantName, DishName FROM Dishes LEFT JOIN Restaurants ON Restaurants.RestaurantID = Dishes.RestaurantID;

SELECT RestaurantName, DishName FROM Restaurants INNER JOIN Dishes ON Restaurants.RestaurantID = Dishes.RestaurantID;

Only products with assigned suppliers will be listed.

An error will be generated due to missing suppliers.

All suppliers will be listed, even if they have no products.

SELECT ProductID, SUM(Quantity) FROM Orders GROUP BY ProductID;

SELECT ProductID, SUM(Quantity) FROM Orders WHERE SUM(Quantity) > 100 GROUP BY ProductID;

SELECT ProductID, SUM(Quantity) FROM Orders GROUP BY ProductID HAVING SUM(Quantity) > 100;

SELECT ProductID, COUNT(Quantity) FROM Orders GROUP BY ProductID HAVING COUNT(Quantity) > 100;

SELECT * FROM Employees FULL JOIN Departments ON Employees.DepartmentID = Departments.DepartmentID;

SELECT * FROM Employees RIGHT JOIN Departments ON Employees.DepartmentID = Departments.DepartmentID;

ELECT * FROM Employees INNER JOIN Departments ON Employees.DepartmentID = Departments.DepartmentID;

SELECT * FROM Employees LEFT JOIN Departments ON Employees.DepartmentID = Departments.DepartmentID;

SELECT DISTINCT CustomerID FROM Orders WHERE YEAR(OrderDate) = 2025

SELECT DISTINCT CustomerID FROM Orders WHERE OrderDate >= '2025-01-01';

SELECT CustomerID FROM Orders WHERE OrderDate LIKE '2025%';

SELECT CustomerID FROM Orders GROUP BY OrderDate;

1NF

3NF

2NF