Problem to summarize parts of a sequence

Question

Hi together,
I'm new here and I only have some basic know how about Oracle PL SQL.
I'd like to create a confusing query in SQL Developer.
I tried to split a sequence into single numbers and multiplied this numbers with different values. By then everything worked fine.
This is the statement to split my sequence:
SELECT
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),1,1)*3),
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),2,1)*1),
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),3,1)*3),
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),4,1)*1),
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),5,1)*3),
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),6,1)*1),
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),7,1)*3)
from dual;
But now i tried to summarize (sum) the output of the multiplication and get an error.
With this statement:
SELECT sum(
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),1,1)*3)+
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),2,1)*1)+
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),3,1)*3)+
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),4,1)*1)+
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),5,1)*3)+
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),6,1)*1)+
(substr(LPAD(CAST(SEQ_LOID.nextval AS number(8)), 7, '0'),7,1)*3))
from dual;
02287. 00000 -  "sequence number not allowed here"
*Cause:    The specified sequence number (CURRVAL or NEXTVAL) is inappropriate
           here in the statement.
*Action:   Remove the sequence number.
Thank's in advance for your help. I appreciate for any kind of hints.
I spent many hours and couldn't find a solution.

Answer 1

Hi,
There are pretty severe restrictions on where sequences can be used.  See the SQL language manual
http://docs.oracle.com/cd/E11882_01/server.112/e26088/pseudocolumns002.htm#sthref45
for details.  It specifially says that you can't use NEXTVAL in a query with a GROUP BY clause.  It doesn't say anything about a query that uses an aggregate function (such as SUM) but no GROUP BY clause, like your query.  Using aggregate functions without a GROUP BY clause produces the same results as "GROUP BY NULL"  (or any constant in place of NULL), so it's easy to imagine that the restriction applies to any query with aggregate functions, whether or not it uses GROUP BY.
What are you trying to do?  Do you really need a sequence to do it?  The analytic ROW_NUMBER function can generate unique, consecutive integers, very much like a sequence.  Could you use ROW_NUMBER fot whatever it is you need?
Assuming you really do need a sequence, you could create a table (perhaps a Global Temporary Table), populate it with values from the sequence, and then use those values any way you want in a query.  Or you could capture one sequence value in a substitution variable, then use that variable any way you want in a query, e.g., using ROW_NUMBER to generate consecutive integers starting with theat number.
If you cvan explain what you need to do, someone can help you find a good way to do it in Oracle.
See the forum FAQ: https://forums.oracle.com/message/9362002