Grouping function in SQL Server
sql server rollup grouping
sql server rollup replace null
sql server rollup grouping replace null
In this video we will discuss the use of Grouping function in SQL Server.
Healthy diet is very important both for the body and mind. If you like Aarvi Kitchen recipes, please support by sharing, subscribing and liking our YouTube channel. Hope you can help.
/ @aarvikitchen5572
This is continuation to Part 104. Please watch Part 104 from SQL Server tutorial before proceeding.
What is Grouping function
Grouping(Column) indicates whether the column in a GROUP BY list is aggregated or not. Grouping returns 1 for aggregated or 0 for not aggregated in the result set.
The following query returns 1 for aggregated or 0 for not aggregated in the result set
SELECT Continent, Country, City, SUM(SaleAmount) AS TotalSales,
GROUPING(Continent) AS GP_Continent,
GROUPING(Country) AS GP_Country,
GROUPING(City) AS GP_City
FROM Sales
GROUP BY ROLLUP(Continent, Country, City)
What is the use of Grouping function in real world
When a column is aggregated in the result set, the column will have a NULL value. If you want to replace NULL with All then this GROUPING function is very handy.
SELECT CASE WHEN
GROUPING(Continent) = 1 THEN 'All' ELSE ISNULL(Continent, 'Unknown')
END AS Continent,
CASE WHEN
GROUPING(Country) = 1 THEN 'All' ELSE ISNULL(Country, 'Unknown')
END AS Country,
CASE
WHEN GROUPING(City) = 1 THEN 'All' ELSE ISNULL(City, 'Unknown')
END AS City,
SUM(SaleAmount) AS TotalSales
FROM Sales
GROUP BY ROLLUP(Continent, Country, City)
Can't I use ISNULL function instead as shown below
SELECT ISNULL(Continent, 'All') AS Continent,
ISNULL(Country, 'All') AS Country,
ISNULL(City, 'All') AS City,
SUM(SaleAmount) AS TotalSales
FROM Sales
GROUP BY ROLLUP(Continent, Country, City)
Well, you can, but only if your data does not contain NULL values. Let me explain what I mean.
At the moment the raw data in our Sales has no NULL values. Let's introduce a NULL value in the City column of the row where Id = 1
Update Sales Set City = NULL where Id = 1
Now execute the following query with ISNULL function
SELECT ISNULL(Continent, 'All') AS Continent,
ISNULL(Country, 'All') AS Country,
ISNULL(City, 'All') AS City,
SUM(SaleAmount) AS TotalSales
FROM Sales
GROUP BY ROLLUP(Continent, Country, City)
Notice that the actuall NULL value in the raw data is also replaced with the word 'All', which is incorrect. Hence the need for Grouping function.
Please note : Grouping function can be used with Rollup, Cube and Grouping Sets
Text version of the video
http://csharp-video-tutorials.blogspo...
Slides
http://csharp-video-tutorials.blogspo...
All SQL Server Text Articles
http://csharp-video-tutorials.blogspo...
All SQL Server Slides
http://csharp-video-tutorials.blogspo...
All Dot Net and SQL Server Tutorials in English
https://www.youtube.com/user/kudvenka...
All Dot Net and SQL Server Tutorials in Arabic
/ kudvenkatarabic
Auf dieser Seite können Sie das Online-Video Grouping function in SQL Server mit der Dauer stunde minuten sekunde in guter Qualität ansehen, das der Benutzer kudvenkat 25 September 2015 hochgeladen hat, den Link mit Freunden und Bekannten teilen, dieses Video wurde auf Youtube bereits 81,119 Mal angesehen und es wurde von 445 den Zuschauern gefallen. Viel Spaß beim Betrachtenden Zuschauern gefallen!
