How to use subqueries in Oracle? - oracle

Question

I have the following table:
table1
-------------------------
date | ID | name
-------------------------
13-jul-15 | 1 | abc
13-jul-15 | 2 | abc
14-jul-15 | 1 | def
13-jul-15 | 3 | abc
15-jul-15 | 3 | def
...
What I want to do is match the ID and represent as below:
date1 | name | date2 | name | ID
------------------------------------------
13-jul-15 | abc | 14-jul-15 | def | 1
13-jul-15 | abc | | | 2
13-jul-15 | abc | 15-jul-15 | def | 3
...
I have used the following code, but not getting the result.
CREATE PROCEDURE get_details ( oresults1 OUT SYS_REFCURSOR ) AS
BEGIN
SELECT *
FROM ((SELECT date, ID FROM table1 WHERE name= "abc") T1
UNION ALL
(SELECT date, ID FROM table1 WHERE name= "def") T2
)
WHERE T1.ID= T2.ID
ORDER BY ID;
END;
What have I done wrong?

Answer 1

Here are a couple of alternatives:
with table1 as (select to_date('13/07/2015', 'dd/mm/yyyy') dt, 1 id, 'abc' name from dual union all
select to_date('13/07/2015', 'dd/mm/yyyy') dt, 2 id, 'abc' name from dual union all
select to_date('14/07/2015', 'dd/mm/yyyy') dt, 1 id, 'def' name from dual union all
select to_date('13/07/2015', 'dd/mm/yyyy') dt, 3 id, 'abc' name from dual union all
select to_date('15/07/2015', 'dd/mm/yyyy') dt, 3 id, 'def' name from dual)
-- end of mimicking your table1. See below for the query
select t1.dt date1,
t1.name name1,
t2.dt date2,
t2.name name2,
t1.id
from table1 t1
left outer join table1 t2 on (t1.id = t2.id and t1.name = 'abc' and t2.name = 'def')
where t1.name = 'abc'
order by t1.id;
DATE1 NAME1 DATE2 NAME2 ID
---------- ----- ---------- ----- ----------
13/07/2015 abc 14/07/2015 def 1
13/07/2015 abc 2
13/07/2015 abc 15/07/2015 def 3
with table1 as (select to_date('13/07/2015', 'dd/mm/yyyy') dt, 1 id, 'abc' name from dual union all
select to_date('13/07/2015', 'dd/mm/yyyy') dt, 2 id, 'abc' name from dual union all
select to_date('14/07/2015', 'dd/mm/yyyy') dt, 1 id, 'def' name from dual union all
select to_date('13/07/2015', 'dd/mm/yyyy') dt, 3 id, 'abc' name from dual union all
select to_date('15/07/2015', 'dd/mm/yyyy') dt, 3 id, 'def' name from dual)
-- end of mimicking your table1. See below for the query
select t1.dt date1,
t1.name name1,
t2.dt date2,
t2.name name2,
t1.id
from (select id, dt, name from table1 where name = 'abc') t1
left outer join (select id, dt, name from table1 where name = 'def') t2 on (t1.id = t2.id)
where t1.name = 'abc'
order by t1.id;
DATE1 NAME1 DATE2 NAME2 ID
---------- ----- ---------- ----- ----------
13/07/2015 abc 14/07/2015 def 1
13/07/2015 abc 2
13/07/2015 abc 15/07/2015 def 3

Answer 2

You can also use pivot function available in Oracle
WITH table_(date#, id#, name#) AS
(SELECT to_date('13-jul-15', 'dd-mon-yy'), 1, 'abc' FROM dual UNION all
SELECT to_date('13-jul-15', 'dd-mon-yy'), 2, 'abc' FROM dual UNION all
SELECT to_date('14-jul-15', 'dd-mon-yy'), 1, 'def' FROM dual UNION all
SELECT to_date('13-jul-15', 'dd-mon-yy'), 3, 'abc' FROM dual UNION all
SELECT to_date('15-jul-15', 'dd-mon-yy'), 3, 'def' FROM dual)
--------
-- End of data preparation
--------
SELECT *
FROM table_
PIVOT (MIN(date#) AS date#, MIN(name#) AS NAME# FOR name# IN ('abc' AS ABC, 'def' AS DEF));
Output
| ID# | ABC_DATE# | ABC_NAME# | DEF_DATE# | DEF_NAME# |
|-----|------------------------|-----------|------------------------|-----------|
| 1 | July, 13 2015 00:00:00 | abc | July, 14 2015 00:00:00 | def |
| 2 | July, 13 2015 00:00:00 | abc | | |
| 3 | July, 13 2015 00:00:00 | abc | July, 15 2015 00:00:00 | def |