sql group by clause

[hisoka]

I read about sql group by clause but I could not understand what it really means and what it does . I would like to know what it is in simple words and what it does ?

[Ingolme]

Did you read the tutorial page? http://www.w3schools.com/sql/sql_groupby.asp

[hisoka]

yes . It was the first tutorial I read before I posted my message . However I could not understand the group by clause

[Ingolme]

I don't really know how to put it simpler than it is in the tutorial.

 

If you have multiple rows with the same value, you use GROUP BY to only return one result with that value. Aggregate functions can be used to operate with the values of all the rows that have been grouped.

[hisoka]

"If you have multiple rows with the same value"

 

I cannot see in the link you gave me :

 

http://www.w3schools...sql_groupby.asp

 

any table that has two rows with the same value !!!

[Ingolme]

They're not showing all the records in the database table on that page, they only show three from each table.Most likely, in the orders table there are multiple different orders with the same ShipperID.

[hisoka]

"If you have multiple rows with the same value, you use GROUP BY to only return one result with that value"

 

is it the function of GROUP BY clause ?

 

what if we have multiple rows with different values, do we use GROUP BY to return only one result ??