Transform column into rows in SQL Server table - sql

Question

I have a query in which I want some columns to be appear as rows.
The query is
Select *
From Emp_mon_day
Where emp_mkey IN (select emp_card_no
from emp_mst
where comp_mkey in (7, 110))
and Year = 2016 and month = 2
and Emp_mkey = 2492
with this output being returned:
Now, I need to show columns Day1, Day2, Day3 as rows in the output with the above query.
How to achieve that?

Answer 1

You can use case an UNPIVOT query like below
Select
comp_mkey,
fmodule_id,
fdepartment_id,
branch_mkey,
entry_department,
dept_mkey,
mkey,
emp_mkey,
entry_date,
month,
year,
day,
data
from
(select * from Emp_mon_day where emp_mkey IN
(select emp_card_no from emp_mst where comp_mkey in
(7,110)) and Year = 2016 and month = 2
and Emp_mkey = 2492) s
unpivot
(
data for day in ([Day1],[Day2]) -- dynamic query can generate all days data
)up
Below is sample test script and output
create table t(comp_mkey int,mont int,yea int,day1 varchar(10),day2 varchar(10))
insert into t values (2,2,2016,'AB','AC')
Select
comp_mkey,
mont,
yea,
day,
data
from
(select * from t) s
unpivot
(
data for day in ([Day1],[Day2]) -- dynamic query can generate all days data
)up
drop table t
Output
If you need all day's data you can either type out all expected columns in this statement
data for day in ([Day1],[Day2], [Day3],[Day4])
Better way would be to convert this into a dynamic query and apply logic for number of days expected in a month

Answer 2

CROSS APPLY can be proven helpful here.
CREATE TABLE [dbo].[emp]
(
[comp_mkey] [INT] NULL,
[mont] [INT] NULL,
[year] [INT] NULL,
[day1] [VARCHAR](10) NULL,
[day2] [VARCHAR](10) NULL
)
INSERT INTO emp VALUES (2, 2, 2016, 'AB', 'AC')
Use following Select statement
SELECT emp.comp_mkey
, emp.mont
, emp.year
, emp_ext.[Day]
, emp_ext.Value
FROM emp
CROSS APPLY
(
VALUES('Day1', emp.day1), ('Day2', emp.day2)
)emp_ext([Day], Value)