SQL Server Table Calculations -


given:

+-----------+---------------+-------------+-------+ |   name    |   item        | year        | value | +-----------+---------------+-------------+-------+ | company | sales         | 2017        |   100 | | company | sales         | 2016        |   100 | | company | sales         | 2015        |   400 | | company | profit        | 2017        |    50 | | company | profit        | 2016        |    50 | | company | profit        | 2015        |   200 | | company b | sales         | 2017        |   200 | | company b | sales         | 2016        |   100 | | company b | profit        | 2017        |    20 | | company b | profit        | 2016        |    20 | +-----------+---------------+-------------+-------+

how use sql transform to:

+----------+---------------+--------+-----------+ |   name   |   year        | margins| 2 yr ave  | +----------+---------------+--------+-----------+ | companya | 2015          |    50% |    null   |   | companya | 2016          |    50% |    50%    |   | companya | 2017          |    50% |    50%    |   | companyb | 2016          |    20% |    null   | | companyb | 2017          |    10% |    15%    | +----------+---------------+--------+-----------+

and 

+----------+---------------+--------+-----------+ |   name   |   year        | compa  | compb     | +----------+---------------+--------+-----------+ | margin   | 2015          |    50% |    null   |   | margin   | 2016          |    50% |    20%    |   | margin   | 2017          |    50% |    10%    |   | 2yr ave  | 2015          |   null |    null   | | 2yr ave  | 2016          |    50% |    null   | | 2yr ave  | 2017          |    50% |    15%    | +----------+---------------+--------+-----------+
  • margin: (profit/sales*100) of given year and
  • 2 year ave: margin year + margin of previous year / 2, null if there no data previous year.

my approach first aggregate once on table using group by compute profit margins each company in each year. then, make second pass using lag() calculate recent 2 year margin average.

with cte (     select         name,         year,         100*max(case when item = 'profit' value end) /             max(case when item = 'sales' value end) margins     yourtable     group         name,         year )  select     name,     year,     margins,     (margins + lag(margins) on (partition name order year)) / 2 [2 yr avg] cte order     name,     year

for second table output, can pivot result query. place code gave cte, , pivot on margin columns.

output:

enter image description here

demo here:

rextester


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