Question

I am using Oracle SQL Developer.
I essentially have a table of pictures that holds the columns:

[DATE_CREATED(date), NUM_of_PICTURES(int)]

and if I do a select *, I would get an output similar to:

01-May-12    12
02-May-12    15
03-May-12    09
...
...
01-Jun-12    20
...
etc.

I am trying to aggregate these sums of pictures into MONTHLY numbers instead of DAILY.

I’ve tried doing something like:

select Month(DATE_CREATED), sum(Num_of_Pictures))
from pictures_table
group by Month(DATE_CREATED);

This outputs an error:

ORA-00904: "MONTH": invalid identifier
00904. 00000 -  "%s: invalid identifier"
*Cause:    
*Action:
Error at Line: 5 Column: 9

Do I have the Month function wrong?

Answer 1

I would be inclined to include the year in the output. One way:

select to_char(DATE_CREATED, 'YYYY-MM'), sum(Num_of_Pictures)
from pictures_table
group by to_char(DATE_CREATED, 'YYYY-MM')
order by 1

Another way (more standard SQL):

select extract(year from date_created) as yr, extract(month from date_created) as mon,
       sum(Num_of_Pictures)
from pictures_table
group by extract(year from date_created), extract(month from date_created)
order by yr, mon;

Remember the order by, since you presumably want these in order, and there is no guarantee about the order that rows are returned in after a group by.