取消表Oracle中的数据

Question

My source is like

**Col1  Col2 Col3  Col4    Col5  Col6**
1     ABC  STAT1  STAT2  COM1  COM2

How do I get below

**Col1 Col2 type Col4   Col5**
1    ABC  STAT STAT1  STAT2
1    ABC  COM  COM1   COM2

I looked at Unpivot, its able to do one column -> one row . But I'm looking for 2 columns into 1 row. Union all would be one option, but I would like to see it using unpivot

Answer 1

My preferred method is a lateral join, but that is not available until Oracle 12c. If you have only two options and your table is not really big, union all is probably sufficient:

select col1, col2, 'STAT' as type, col3 as col4, col4 as col5
from t
union all
select col1, col2, 'COM' as type, col5, col6
from t;

If scanning the table twice is a performance issue, there are other options as well.

A pretty simple way without unpivot is a join :

select t.col1, t.col2, tt.type,
       (case when tt.type = 'STAT' then col3 else col5 end),
       (case when tt.type = 'STAT' then col4 else col6 end)
from t cross join
     (select 'STAT' as type from dual union all
      select 'COM' as type from dual
     ) tt;