HOW TO USE ORDER BY CLAUSE INSIDE UNION ALL QUERY
(USING ORDER BY CLAUSE IN EACH INDIVIAUAL QUERIES & JOIN THEM USNING UNION ALL)
Author JP Vijaykumar
Date March 8th 2016
create table temp_jp(id number,name varchar2(20));
insert into temp_jp values(1,'Veeksha');
insert into temp_jp values(2,'Saketharama');
insert into temp_jp values(3,'Vineela');
commit;
SQL> select * from temp_jp;
ID NAME
---------- --------------------
1 Veeksha
2 Vineela
3 Saketharama
--Here I am using two select queries with ORDER BY clause and join them with a UNION ALL.
SQL> select * from temp_jp where name like 'S%' order by 1
union all
select * from temp_jp where name like 'V%' order by 1; 2 3
union all
*
ERROR at line 2:
ORA-00933: SQL command not properly ended
--I modified the query as show below and executed successfully.
SQL> with t1 as (select * from temp_jp where name like 'S%' order by name),
t2 as (select * from temp_jp where name like 'V%' order by name)
select * from t1
union all
select * from t2; 2 3 4 5
ID NAME
---------- --------------------
2 Saketharama
1 Veeksha
3 Vineela
--For the convenience of readability, I want to insert a blank line between the two queries.
SQL> with t1 as (select * from temp_jp where name like 'S%' order by name),
2 t2 as (select * from temp_jp where name like 'V%' order by name)
3 select * from t1
4 union all
5 select null from dual --NEED TO INSERT A BLANK LINE INBETWEEN
6 union all
7 select * from t2;
select null from dual --NEED TO INSERT A BLANK LINE INBETWEEN
*
ERROR at line 5:
ORA-01789: query block has incorrect number of result columns
--I need to select equal number of null values from DUAL, as the number of columns
--were included in the other queries.
SQL> with t1 as (select * from temp_jp where name like 'S%' order by name),
2 t2 as (select * from temp_jp where name like 'V%' order by name)
select * from t1
union all
3 select null,null from dual --NEED TO SELECT EQUAL NUMBER OF NULL COLUMNS, AS WERE SELECTED IN OTHER QUERIES
union all
select * from t2; 4 5 6 7
ID NAME
---------- --------------------
2 Saketharama
1 Veeksha
3 Vineela
3 rows selected.
--Here I generated two sql quereis with ORDER BY cluse and joining with UNION ALL,
--and seperated the two sql queries with a blank line.
Happy scripting.