Sorting in a Union Clause

Question

We have a table which has data a following
Regime Country EffectiveFrom
USTax          US     01-09-1998               
UkTax UK 01-09-1983
CATax US 01-09-2010
FRTax FR 01-09-1999
We have a bind variable :bCountry.Which we are passing to the country column.
Results should be :
1. All the Regimes which belong to :bCountry passed and sorted by
a. Regimes in alphabetical ascending sort within each Country
b. 'EffectiveFrom' in descending order within Country and Regime.
Plus
1. All the Regimes which are not in :bCountry passed and sorted by
a. Tax Regime Code in alphabetical ascending sort within each Country
b. 'Effective Start Date' in descending order within Country and Tax Regime Code.
So i am planning to write the query as
select regime, country,effectivefrom
from reg_tbl
where country = :bCountry
union all
select regime, country,effectivefrom
from reg_tbl
where country <> :bCountry
But iam not sure of how to do the sorting in this case.
Please help

Answer 1

Hi,
Whenever you have a question, it helps if you post sample data in an executable form, such as CREATE TABLE and INSERT statements, and also post the results you want from that data.
You can ORDER BY a CASE expression:
ORDER BY  country
,            CASE
          WHEN  country = :bCountry
          THEN  regime
          ELSE  tax_regime_code
             END
,       effective_from     DESCAs always, all values returned by the CASE expression must be the same type (e.g., all VARCHAR2s or all DATEs).