Group By include joins in SQL Server

Question

Group By includes having joins in SQL Server  how can we use joins when getting the data from multiple tables any order we need to join while fetching the data or randomly joins tables to get the result

Tuhin Paul · Answer

There is an application for reading articles or news from a database and the users can select an article. The application will fetch the article content from the database process it and use text-to-speech to read it aloud. Example Schema: Articles ArticleID (Primary Key) Title Content AuthorID (Foreign Key to Authors) CategoryID (Foreign Key to Categories) Views (Number of views) Authors AuthorID (Primary Key) Name Categories CategoryID (Primary Key) Name CREATE TABLE Articles ( ArticleID INT PRIMARY KEY IDENTITY(11) Title NVARCHAR(255) Content NVARCHAR(MAX) ); INSERT INTO Articles (Title Content) VALUES ('The Future of AI' 'Artificial intelligence is rapidly evolving and is set to change the world...') ('Health Benefits of Meditation' 'Meditation has been practiced for thousands of years...') ('Technological Advancements in 2025' 'By 2025 new technologies will reshape the way we live and work...'); We will create a query to: Join the Articles  Authors  and Categories tables. Group the results by Category and Author . Filter the results using HAVING to show only articles with a minimum number of views and/or words. SELECT a.AuthorID au.Name AS AuthorName c.CategoryID c.Name AS CategoryName COUNT(a.ArticleID) AS TotalArticles SUM(LEN(a.Content) - LEN(REPLACE(a.Content ' ' '')) + 1) AS TotalWords -- Counting words in the article SUM(a.Views) AS TotalViews FROM Articles a JOIN Authors au ON a.AuthorID = au.AuthorID JOIN Categories c ON a.CategoryID = c.CategoryID GROUP BY a.AuthorID au.Name c.CategoryID c.Name HAVING SUM(a.Views) > 1000 -- Only include articles with more than 1000 views AND SUM(LEN(a.Content) - LEN(REPLACE(a.Content ' ' '')) + 1) > 500 -- Only include articles with more than 500 words ORDER BY TotalViews DESC; The Articles table is joined with the Authors table on AuthorID and with the Categories table on CategoryID . These joins link the article to its author and category. We GROUP BY a.AuthorID  au.Name  c.CategoryID  and c.Name to group articles by both their author and category. We calculate the total number of articles ( COUNT(a.ArticleID) ) total number of words ( SUM(LEN(a.Content) - LEN(REPLACE(a.Content ' ' '')) + 1) ) and total views ( SUM(a.Views) ). Using GROUP BY  HAVING  and JOIN in SQL Server allows us to aggregate data from multiple tables and apply complex filtering and grouping logic. In this case we filtered articles based on their word count and views and displayed them in a structured way (grouped by author and category).

Sangeetha S · Answer

simple example of a SQL query using GROUP BY with joins: SELECT c.CustomerName COUNT(o.OrderID) AS OrderCount FROM Customers c INNER JOIN Orders o ON c.CustomerID = o.CustomerID INNER JOIN Products p ON o.ProductID = p.ProductID GROUP BY c.CustomerName;

Jignesh Kumar · Answer

Hello Kiran In simple words We need to understand the data and table structure in the query because the order of tables used in the joins is important. Follow the below two points Perform the necessary joins before applying the GROUP BY clause. This ensures all the columns needed for grouping or aggregation are available after the joins.