I have a row that should be duplicated in certain conditions. Example:
Case 1:
a b c d e
---------------
1 4 25 10 NULL
if e is Null, display a, b and c:
1 4 25
Case 2:
a b c d e
---------------
1 4 25 10 55
if e is not Null, duplicate the row
1 4 25 => column a,b,c
1 4 10 => column a,b,d
Use this query
Using union you can achieve this use case
select a,b,c from table
union all
select a,b,d from table where e is not null
If you don't want to scan the table twice, then you can use cross joinand some logic:
select a, b,
(case when n = 1 then c else d end)
from t cross join
(select 1 as n union all select 2) n
where n = 1 or
(n = 2 and e is not null);
