SQL Server creating two tables and comparing them - sql

Question

I have a table with 3 columns (in SQL Server 2012). One of the columns is a date column. What I would like to do is split the table for two specified dates and merge them into one table with an extra field. Hopefully the example below will explain.
Example of what I currently have.
Company date no_employees
ABC 2014-05-30 35
DEF 2014-05-30 322
GHI 2014-05-30 65
JKL 2014-05-30 8
MNO 2014-05-30 30
ABC 2014-01-01 33
DEF 2014-01-01 301
GHI 2014-01-01 70
MNO 2014-01-01 30
What I would like a query to return for me (not sure if its possible),
Company start date no_employees end date no_employees diff
ABC 33 35 2
DEF 301 322 21
GHI 70 65 -5
JKL 0 8 8
MNO 30 30 0

Answer 1

PIVOT (and COALESCE to generate the 0s) seems to do it:
declare #t table (Company char(3),[date] date,no_employees int)
insert into #t(Company,[date],no_employees) values
('ABC','2014-05-30',35 ),
('DEF','2014-05-30',322 ),
('GHI','2014-05-30',65 ),
('JKL','2014-05-30',8 ),
('MNO','2014-05-30',30 ),
('ABC','2014-01-01',33 ),
('DEF','2014-01-01',301 ),
('GHI','2014-01-01',70 ),
('MNO','2014-01-01',30 )
select Company,
COALESCE(start,0) as start,
COALESCE([end],0) as [end],
COALESCE([end],0)-COALESCE(start,0) as diff
from
(select
Company,
CASE WHEN [date]='20140530' THEN 'end'
ELSE 'start' END as period,
no_employees
from #t
where [date] in ('20140101','20140530')
) t
pivot (MAX(no_employees) for period in ([start],[end])) u
Result:
Company start end diff
------- ----------- ----------- -----------
ABC 33 35 2
DEF 301 322 21
GHI 70 65 -5
JKL 0 8 8
MNO 30 30 0
This could easily be parameterized for the specific start and end dates to use.
Also, at the moment I'm using MAX because we have to have an aggregate in PIVOT, even though here the sample data contains a maximum of one row. If there's a possibility of multiple rows existing for the start or end date, we'd need to know how you want that handled.

Answer 2

declare #lowdate date = '2014-01-01'
declare #highdate date = '2014-05-30'
;with x as
(
select company, min(no_employees) no_employees
from #t records
where recorddate = #lowdate
group by company
), y as
(
select company, max(no_employees) no_employees
from #t records
where recorddate = #highdate
group by company
)
select coalesce(x.company, y.company) company,
coalesce(x.no_employees, 0) start_no_employees,
coalesce(y.no_employees, 0) end_no_employees,
coalesce(y.no_employees, 0) - coalesce(x.no_employees, 0) diff
from
x full outer join y
on
x.company = y.company

Answer 3

Create Table #temp(Company varchar(10), CDate date,emp int)
Select T1.Company,T1.emp,T2.emp,(T1.emp-T2.emp) Diff
from #temp T1
inner join #temp T2 On T1.Company=T2.Company and T1.CDate<T2.CDate
Order by T1.Company,T1.CDate

Answer 4

declare #t table (Company char(3),[date] date,no_employees int)
insert into #t(Company,[date],no_employees) values
('ABC','2014-05-30',35 ),
('DEF','2014-05-30',322 ),
('GHI','2014-05-30',65 ),
('JKL','2014-05-30',8 ),
('MNO','2014-05-30',30 ),
('ABC','2014-01-01',33 ),
('DEF','2014-01-01',301 ),
('GHI','2014-01-01',70 ),
('MNO','2014-01-01',30 )
select Company,MIN(no_employees),MAX(no_employees),CASE WHEN MIN(no_employees) = MAX(no_employees) then MAX(no_employees) else
MIN(no_employees) - MAX(no_employees) end as cNT from #t
GROUP BY Company

Answer 5

select the companies. Outer join the start date records. Outer join the end date records. Use coalesce to show 0 instead of null.
select
company,
coalesce(rec20140101.no_employees, 0) as empno_start,
coalesce(rec20140530.no_employees, 0) as empno_end
from
(
select distinct company
from records
) companies -- or use a company table if you have one
left join
(
select company, no_employees
from records
where recorddate = '2014-01-01'
) rec20140101
on rec20140101.company = companies.companyrec
left join
(
select company, no_employees
from records
where recorddate = '2014-05-30'
) rec20140530
on rec20140530.company = companies.company);
EDIT: And here is a way to scan the table just once. It's even a little shorter ;-)
select
company,
coalesce(min( case when recorddate = '2014-05-30' then no_employees end ), 0) as empno_start,
coalesce(min( case when recorddate = '2014-01-01' then no_employees end ), 0) as empno_end
from records
group by company;

Answer 6

Try this:
;with cte as
(select
COALESCE(src.company, tgt.company) company
isnull(tgt.no_employees,0) 'start date no_employees',
isnull(src.no_employees , 0) 'end date no_employees'
from
tbl src
full outer join tbl tgt on src.company = tgt.company and src.date <> tgt.date
where (src.date = (select max(date) from tbl) or src.date is null)
and (tgt.date = (select min(date) from tbl) or tgt.date is null)
)
select *, [end date no_employees] - [start date no_employees] diff
from cte