select one column, split to multiple columns - sql

Question

I have a table in Oracle Database like below:
res_code column1 ...
-------------------------------
001 A
002 B
003 C
004 D
005 E
I want to select from this table to get the result like:
res_code1 res_code2
-------------------------------
001 002
003 004
005 ...
tip: res_code1 and res_code2 both belongs to res_code, can't be duplicated.
Is is possible using sql?

Answer 1

You can do this simply with an SQL like:
with odds as
(
select res_code, cast(res_code as int) as rn
from myTable
where mod(cast(res_code as int) ,2) =1
),
evens as
(
select res_code, cast(res_code as int) as rn
from myTable
where mod(cast(res_code as int) ,2) =0
)
select odds.res_code as res_code1, evens.res_code as res_code2
from odds
left join evens on evens.rn = odds.rn+1;

Answer 2

you can try this, use row_number to make rn then do MOD to split the group.
Doing some arithmetic in main query.
CREATE TABLE T(
res_code VARCHAR(50),
column1 VARCHAR(50)
);
INSERT INTO T VALUES ('001' ,'A');
INSERT INTO T VALUES ('002' ,'B');
INSERT INTO T VALUES ('003' ,'C');
INSERT INTO T VALUES ('004' ,'D');
INSERT INTO T VALUES ('005' ,'E');
Query 1:
with cte as (
select t1.*,
MOD(row_number() over (order by column1) ,2) rn,
ceil(row_number() over (order by column1) / 2) grp1
from T t1
)
select MAX(CASE WHEN rn = 1 THEN t1.RES_CODE END) res_code1,
MAX(CASE WHEN rn = 0 THEN t1.RES_CODE END) res_code2
from cte t1
group by grp1
Results:
| RES_CODE1 | RES_CODE2 |
|-----------|-----------|
| 001 | 002 |
| 003 | 004 |
| 005 | (null) |

Answer 3

Use cursor to do double fetch and single insert:
declare #res_code1 nvarchar(100), #res_code2 nvarchar(100), #even int
declare #newtable table(res_code1 nvarchar(100), res_code2 nvarchar(100))
declare cur cursor for (select res_code from #mytable)
open cur
-- assume first 2 rows are available
fetch next from cur into #res_code1
fetch next from cur into #res_code2
-- set #even to 1 meaning even value has been fetched
set #even = 1
while ##FETCH_STATUS = 0
begin
if #even = 0
begin
-- fetch #res_code2
fetch next from cur into #res_code2
set #even = 1
end
else
begin
-- insert into table since #even = 1 (has even number)
insert into #newtable values(#res_code1,#res_code2)
-- fetch #res_code1
fetch next from cur into #res_code1
set #even = 0
end
end
-- insert the last odd
if #even = 1
insert into #newtable values(#res_code1,'')