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<PMDORAIS_at_gmail.com> a écrit dans le message de news: 1162234976.272547.259500_at_h48g2000cwc.googlegroups.com...
| Hi,
|
| First, i'm a newbie with sql and i would like to do the following:
|
| I want to extract a random sample for each value of a certain field in
| a table;
|
|
| For example
|
|
| table
|
| clientid name group
| 1 xxx a
| 2 yyy b
| 3 ccc c
|
| etc...
|
| and i would like a sample of 20% of the records for each group (a, b,
| c).... how can i do that...??
|
| thanks!
|
Something like (GROUP and NAME are reserved words don't use them):
with
data as (
select clientid, nom, groupe,
row_number () over (partition by groupe order by dbms_random.value) rn, count(*) over (partition by groupe) cntfrom mytable
Regards
Michel Cadot
Received on Mon Oct 30 2006 - 14:09:51 CST