Necessity of Group by CLAUSE

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Necessity of Group by CLAUSE

Post by Aashiq » Thu Feb 23, 2012 5:38 am

Could you please let me know the importance of Group by CLAUSE in SQL through an example.

I have read in few places where it has been said that GROUP by clause sorts the results to apply functions that consolidates the data.

If you could give some more explanation about this CLAUSE, that will be more helpful for me.
"Helping hand is better than praying lips"

fredrick andrews
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Post by fredrick andrews » Thu Feb 23, 2012 7:07 am

If there is an orders table with customers and price of the goods they have bought.
Then, If you want to get the total amount they have spent on the goods, the below query will help.


SELECT Customer,SUM(Price) FROM Qual.Orders
GROUP BY Customer;

Customer SUM(Price)
________ __________
Amar 1000
Akbar 2000
Antony 3000

Essentially, it gives you the breakdown of your query by the fields used in the GroupBy clause.

Note: Whatever cols you give in the GROUP BY clause should be mentioned in the SELECT statement too.


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