Could you help this query

Question

hi to all
i have table called period which has the four columns id(p.key),name,parent_id,level
i have 3 different types of periods for eg
101 2009 null 1
102 Q1 101 2
103 Jan 102 3
so here parent_id is also a period , and have Q1,Q2,Q3,Q4 belong to level 2 and all the months belong to level 3
Q1 has Jan,Feb,March and Q2 has Apr,May,Jun, .... Q4 has Oct,Nov,Dec months as childs
now my question is to show the data for a year 2009 l
displaying 2nd level and immeadetly its sub childs to it like
id              name        level
1096     Q1     2
1097     JAN     3
1098     FEB     3
1099     MAR     3
1100     Q2     2
1101     APR     3
1102     MAY     3
1103     JUN     3
1104     Q3     2
1105     JUL     3
1106     AUG     3
1107     SEP     3
1108     Q4     2
1109     OCT     3
1110     NOV     3
1111     DEC     3
1676     Annual     2( which does not have any more childs but still it is a child of 2009)
1675     N/A     2( which does not have any more childs but still it is a child of 2009)
thanks and regards
santhosh

Answer 1

if I understand correctly this is all bout ordering the data. So we just have to find the correct order by clause.
Since you order by a date the basic principle is to convert all the differnt strings into a date value. Then order on it.
example untested
order by case when level = 3 then to_date(name,'MON')
             when level = 2 and name like 'Q%' then add_months(to_date('0101','ddmm'),(to_number(substr(name,2,1))-1)*3) 
             when level = 2 and name = 'Annual' then to_date('3112','ddmm')
             when level = 2 and name = 'N/A' then to_date('3112','ddmm')
             when level = 1 then to_date('YYYY')
             end,
             levelyou can also create a kind of hierarchical select, but I doubt that this would be faster.
My prefered solution would be to add an additional column of datatype date. Fill it with the correct days and then order on it and on the level.
Btw: With your result data you could order simply on ID, but I doubt if this can be guaranteed. So I do not recommend it.
Edited by: Sven W. on Sep 23, 2009 10:06 AM - corrected level 3 function