Alias Calculation

Question

Hi Gurus,
I got a doubt in a query I´m creating here.
That´s the point:
I need to list all table partitions which are older than sysdate - 2 days, because I´ll need to drop them.
I got a query where I´m able to see all date of all partitions.
select table_name,
partition_name,
trim (
'''' from regexp_substr (
extractvalue (
dbms_xmlgen.
getxmltype (
'select high_value from all_tab_partitions where table_name='''
|| table_name
|| ''' and table_owner = '''
|| table_owner
|| ''' and partition_name = '''
|| partition_name
|| ''''),
'//text()'),
high_value_in_date_format
from all_tab_partitions
where table_name = 'EVENTS' and table_owner = 'ESECDBA'
TABLE_NAME PARTITION_NAME
HIGH_VALUE_IN_DATE_FORMAT
EVENTS P_20100303090000
2010-03-03 09:00:00
EVENTS P_20100303110000
2010-03-03 11:00:00
EVENTS P_20100303130000
2010-03-03 13:00:00
TABLE_NAME PARTITION_NAME
HIGH_VALUE_IN_DATE_FORMAT
EVENTS P_20100303150000
2010-03-03 15:00:00
EVENTS P_20100303170000
2010-03-03 17:00:00
EVENTS P_20100303190000
2010-03-03 19:00:00
TABLE_NAME PARTITION_NAME
HIGH_VALUE_IN_DATE_FORMAT
EVENTS P_20100303210000
2010-03-03 21:00:00
EVENTS P_20100303230000
2010-03-03 23:00:00
EVENTS P_FILLER_24
2009-11-26 03:00:00
TABLE_NAME PARTITION_NAME
HIGH_VALUE_IN_DATE_FORMAT
EVENTS P_MAX
EVENTS P_MIN
2009-11-18 03:00:00
1175 rows selected.
The date which I need to compare I store in alias high_value_in_date_format but I´m not able to do a simple compare with it, as:
SQL> select table_name,
2 partition_name,
3 trim (
4 '''' from regexp_substr (
5 extractvalue (
6 dbms_xmlgen.
7 getxmltype (
8 'select high_value from all_tab_partitions where table_name='''
9 || table_name
10 || ''' and table_owner = '''
11 || table_owner
12 || ''' and partition_name = '''
13 || partition_name
14 || ''''),
15 '//text()'),
16 '''.*?'''))
17 high_value_in_date_format
18 from all_tab_partitions
19 where table_name = 'EVENTS'
20 and table_owner = 'ESECDBA'
21 and high_value_in_date_format < to_date ('sysdate', 'syyyy-mm-dd hh24:mi:ss')-2;
where table_name = 'EVENTS'
ERROR at line 19:
ORA-00904: "HIGH_VALUE_IN_DATE_FORMAT": invalid identifier
Is there a way to use the values returned in high_value_in_date_format to compare with sysdate - 2 days ???
Thanks in advance!
Regards,
Leonardo

Answer 1

Nicolas,
I solved the error including the "to_char" function.
select * from (select table_name,
partition_name,
trim (
'''' from regexp_substr (
extractvalue (
dbms_xmlgen.
getxmltype (
'select high_value from all_tab_partitions where table_name='''
|| table_name
|| ''' and table_owner = '''
|| table_owner
|| ''' and partition_name = '''
|| partition_name
|| ''''),
'//text()'),
high_value_in_date_format
from all_tab_partitions
where table_name = 'EVENTS' and table_owner = 'ESECDBA')
where high_value_in_date_format < to_char (to_date(sysdate -2))
order by table_name, partition_name
But I checked with I´m receiving the newest partitions of the table mentioned but this is another problem...
For example:
SQL> select sysdate from dual;
SYSDATE
25-FEB-10
When I query the select, I got all partitions, including the recent created partitions, as above:
TABLE      PARTITION_NAME        HIGH_VALUE_IN_DATE_FORMAT
EVENTS     P_20100303190000     2010-03-03 19:00:00
EVENTS     P_20100303210000     2010-03-03 21:00:00
EVENTS     P_20100303230000     2010-03-03 23:00:00
Thanks a lot to help me.
Regards,
Leonardo