How to union a hardcoded row after each grouped result - sql

Question

After every group / row i want to insert a hardcoded dummy row with a bunch of 'xxxx' to act a separator.
I would like to use oracle sql to do this query. i can execute it using a loop but i don't want to use plsql.

Answer 1

As the others suggest, it is best to do it on the front end.
However, if you have a burning need to be done as a query, here is how.
Here I did not use the rownum function as you have already done. I assume, your data is returned by a query, and you can replace my table with your query.
I made few more assumptions, as you have data with row numbers in it.
[I am not sure what do you mean by not PL/SQL]
Select Case When MOD(rownm, 2) = 0 then ' '
Else to_char((rownm + 1) / 2) End as rownm,
name, total, column1
From
(
select (rownm * 2 - 1) rownm,name, to_char(total) total ,column1 from t
union
SELECT (rownm * 2) rownm,'XXX' name, 'XXX' total, 'The row act .... ' column1 FROM t
) Q
Order by Q.rownm;
and here is the fiddle

Answer 2

Since you're already grouping the data, it might be easier to use GROUPING SETS instead of a UNION.
Grouping sets let you group by multiple sets of columns, including the same set twice to duplicate rows. Then the GROUP_ID function can be used to determine when the fake values should be used. This code will be a bit smaller than a UNION approach, and should be faster since it doesn't need to reference the table multiple times.
select
case when group_id() = 0 then name else '' end name,
case when group_id() = 0 then sum(some_value) else null end total,
case when group_id() = 1 then 'this rows...' else '' end column1
from
(
select 'jack' name, 22 some_value from dual union all
select 'jack' name, 1 some_value from dual union all
select 'john' name, 44 some_value from dual union all
select 'john' name, 1 some_value from dual union all
select 'harry' name, 1 some_value from dual union all
select 'harry' name, 1 some_value from dual
) raw_data
group by grouping sets (name, name)
order by raw_data.name, group_id();

Answer 3

You can use row generator technique (using CONNECT BY) and then use CASE..WHEN as follows:
SQL> SELECT CASE WHEN L.LVL = 1 THEN T.ROWNM END AS ROWNM,
2 CASE WHEN L.LVL = 1 THEN T.NAME
3 ELSE 'XXX' END AS NAME,
4 CASE WHEN L.LVL = 1 THEN TO_CHAR(T.TOTAL)
5 ELSE 'XXX' END AS TOTAL,
6 CASE WHEN L.LVL = 1 THEN T.COLUMN1
7 ELSE 'This row act as separator..' END AS COLUMN1
8 FROM T CROSS JOIN (
9 SELECT LEVEL AS LVL FROM DUAL CONNECT BY LEVEL <= 2
10 ) L ORDER BY T.ROWNM, L.LVL;
ROWNM NAME TOTAL COLUMN1
---------- ---------- ----- ---------------------------
1 Jack 23
XXX XXX This row act as separator..
2 John 45
XXX XXX This row act as separator..
3 harry 2
XXX XXX This row act as separator..
4 roy 45
XXX XXX This row act as separator..
5 Jacob 26
XXX XXX This row act as separator..
10 rows selected.
SQL>