SQL group by with Year() function

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SQL group by with Year() function

Author

Topic

madhan
Yak Posting Veteran

59 Posts

Posted - 2014-06-19 : 12:38:08

[code]
select empid,orderdate from [Sales].[Orders] WHERE custid = 71
group by empid,orderdate
[/code]

sample data resultset:
empid orderdate
1 2006-12-25
1 2007-12-24
1 2007-12-23
1 2008-12-23
1 2008-04-24

[code]
select empid,year(orderdate) from [Sales].[Orders] WHERE custid = 71
group by empid,year(orderdate)

[/code]

sample data resultset:
empid orderdate
1 2006
1 2007
1 2008

why is the year() gets only one year when worked with groupby. when empid =1 the year 2007 has 2 records and 2008 has 2 records in first select and when I used year(orderdate) in secong select only one year for each is selected. I don't understand why is this happening. Please help me understand this....

Lamprey
Master Smack Fu Yak Hacker

4614 Posts

Posted - 2014-06-19 : 13:05:46

It's "aggregating" the data. If you add COUNT(*) as one of the columns, you will see that SQL is aggregating 2 rows into one based on your GROUP BY clause.

gbritton
Master Smack Fu Yak Hacker

2780 Posts

Posted - 2014-06-19 : 13:07:28

You're only projecting the groups (empid, year(orderdate)) and the results are correct. Did you want to count the records per year instead?

e.g.


select count(*) empids, year(orderdate) 'year' from [Sales].[Orders] WHERE custid = 71
group by year(orderdate)

madhan
Yak Posting Veteran

59 Posts

Posted - 2014-06-19 : 14:28:09

Thanks for the help, I understood.

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