How to select unique 100 accounts

Question

I have a sub_accont table associated with account. An account number can have multiple sub_account associated with it. How do i get unique 100 accounts. An account can be active or suspended (A or S).
I am trying the following query:
select distinct(s.account) from s.sub_account where s.sub_account_status in ('A', 'S') and rownum<=100;
When I do that I am getting less than 50 distinct account numbers. Thanks in advance for your help.

Answer 1

Hi,
If you want to use ROWNUM, do it this way:
WITH  got_accounts AS
    SELECT DISTINCT  account
    FROM             s.sub_account      -- I'm guessing s is the schema name
    WHERE            account_status IN ('A', 'S')
SELECT  account
FROM    got_accounts
WHERE   ROWNUM  <= 100;
ROWNUM is computed as the rows are fetched.  DISTINCT is applied after the rows have all been fetched, and the WHERE clause has been evaluated.  The query above computes ROWNUM on values as they are being fetched from the sub-query, that is, after the filtering for account_status has taken place, and the distinct values have been identified.
Depending on your exact requirements, you might want to use the analytic ROW_NUMBER or DENSE_RANK function instead of ROWNUM.
I hope this answers your question.
If not, post  a little sample data (CREATE TABLE and INSERT statements, relevant columns only) for all tables involved, and also post the results you want from that data.
Explain, using specific examples, how you get those results from that data.
Always say which version of Oracle you're using (e.g., 11.2.0.2.0).
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