The following SQL scripts create a view by taking 30% random samples from a table.
Step 1 . Create random numbers within range of 0 and 99 (100 bins).
create table tbl_app_id_w_rnd as select app_id,
mod(abs(dbms_random.random()),100) rnd from CELL_PHONE_SERVICE_APPS;
Step 2. Create a view that contains 30% of the records.
create view v_data_testing
as select a.* from CELL_PHONE_SERVICE_APPS a,
tbl_app_id_w_rnd b where a.app_id=b.app_id and rnd < 30;
Please see a newer post. dbms_random.value is a better function than dbms_random.random.
Wednesday, August 29, 2012
Random Sampling using SQL
Subscribe to: Post Comments (Atom)
Post a Comment