SQL - 如何计算列的唯一组合

Question

I'm not sure if this is possible but I want to count the number of unique value in a table. I know to count the number of unique folderIDs I do:

select count(folderid) from folder

but I want the count of the number of unique combination of folderid and userid in the folder table. Is there a way to do this?

Answer 1

select count(*) from (
  select distinct folderid, userid from folder
)

Answer 2

select count(*) from (
    select folderId, userId
    from folder
    group by folderId, userId
) t

Answer 3

This will give you the count of unique folderid and userid combinations:

SELECT count(*)
  FROM (
        SELECT DISTINCT
               folderid,
               userid
          FROM folder
);

Hope it helps...

Answer 4

SELECT super_group_account_id,
sub_group_account_id,
(super_group_account_id, ' ', sub_group_account_id),
Count ( (super_group_account_id, ' ', sub_group_account_id))
FROM super_sub_group_mapping
GROUP BY (super_group_account_id, ' ', sub_group_account_id)
HAVING Count ( (super_group_account_id, ' ', sub_group_account_id)) > 1

Answer 5

i think you can try to group the select statement with folder id

eg.

i have a table

folderid userid

1 11

1 11

2 12

2 12

3 13

3 13

Query is

select count(folderid) from testtable group by folderid, userid

Answer 6

select APPRSL_ID,SECTION_ID, count(APPRSL_ID||SECTION_ID)
from REMARKSBYEACHSECTION 
group by APPRSL_ID,SECTION_ID
having count(APPRSL_ID||SECTION_ID)>1 ;