Check value for every month in a year in T-sql using cursor - tsql

Question

I need a example of a cursor for my meter system, where the system reads the meter every month.
The cursor needs to check, that every meter has a reading registered in the current year. For meters with missing readings, an estimated value is added, such that the daily consumption is like the daily comsumption in the previous period plus 15%. In no previous period exiss, the above Kwh value is used.

Answer 1

How about something like this. (The MonthSeed table could become a real table in your database)
declare #MonthSeed table (MonthNumber int)
insert into #MonthSeed values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12)
-- assumes declared table "Reading" with fields ( Id int, [Date] datetime, MeterNo varchar(50), Consumption int )
select
m.MeterNo,
r.Date,
calculatedConsumption = isnull(r.Consumption, -- read consumption
isnull((select max(r2.Consumption) Consumption from Reading r2 where datepart(month, r2.Date) = (m.MonthNumber - 1) and r2.MeterNo = m.MeterNo) * 1.15, -- previous consumption + 15%
9999)) -- default consumption
from
(select distinct
MeterNo,
MonthNumber
from
Reading, #MonthSeed) m
left join
Reading r on r.MeterNo = m.MeterNo and datepart(month, r.Date) = m.monthNumber
EDIT FOLLOWING COMMENTS - EXAMPLE OF ADDING MISSING READINGS
As commented need to include an insert before the select insert into Reading (MeterNo, Date, Consumption) and making use of the left join to the reading table include a check for the reading id to be null ie missing where r.Id is null.
I noticed that this would result in null date entries when inserting into the reading table. So I included a date aggregate in the main sub-select Date = dateadd(month, monthnumber, #seeddate); the main select was amended to show a date for missing entries isnull(r.Date, m.Date),
I've calculated the #SeedDate to be the 1st of the current month one year ago but you may want to pass in an earlier date.
declare #MonthSeed table (MonthNumber int)
insert into #MonthSeed values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12)
-- assumes declared table "Reading" with fields ( Id int, [Date] datetime, MeterNo varchar(50), Consumption int )
declare #SeedDate datetime = (select dateadd(month, datediff(month, 0, getdate())-12, 0)) -- this month, last year
insert into Reading (MeterNo, Date, Consumption)
select
m.MeterNo,
isnull(r.Date, m.Date),
calculatedConsumption =
isnull(r.Consumption, -- read consumption
isnull(1.15 * (select max(r2.Consumption) Consumption
from Reading r2
where datepart(month, r2.Date) = (m.MonthNumber - 1)
and r2.MeterNo = m.MeterNo), -- previous consumption + 15%
9999)) -- default consumption
from
(select distinct
MeterNo,
MonthNumber,
Date = dateadd(month, monthnumber, #seeddate)
from
Reading
cross join
#MonthSeed) m
left join
Reading r on r.MeterNo = m.MeterNo and datepart(month, r.Date) = m.monthNumber
where
r.Id is null
select * from Reading

Answer 2

(The following assumes SQL Server 2005 or later.)
Scrounge around in here and see if there's anything of value:
declare #StartDate as Date = '2012-01-01'
declare #Now as Date = GetDate()
declare #DefaultConsumption as Int = 2000 -- KWh.
declare #MeterReadings as Table
( MeterReadingId Int Identity, ReadingDate Date, MeterNumber VarChar(10), Consumption Int )
insert into #MeterReadings ( ReadingDate, MeterNumber, Consumption ) values
( '2012-01-13', 'E154', 2710 ),
( '2012-01-19', 'BR549', 650 ),
( '2012-02-15', 'E154', 2970 ),
( '2012-02-19', 'BR549', 618 ),
( '2012-03-16', 'BR549', 758 ),
( '2012-04-11', 'E154', 2633 ),
( '2012-04-20', 'BR549', 691 )
; with Months ( Month ) as (
select #StartDate as [Month]
union all
select DateAdd( mm, 1, Month )
from Months
where Month < #Now
),
MeterNumbers ( MeterNumber ) as (
select distinct MeterNumber
from #MeterReadings )
select M.Month, MN.MeterNumber,
MR.MeterReadingId, MR.ReadingDate, MR.Consumption,
Coalesce( MR.Consumption, #DefaultConsumption ) as [BillableConsumption],
( select Max( ReadingDate ) from #MeterReadings where MeterNumber = MN.MeterNumber and ReadingDate < M.Month ) as [PriorReadingDate],
( select Consumption from #MeterReadings where MeterNumber = MN.MeterNumber and ReadingDate =
( select Max( ReadingDate ) from #MeterReadings where MeterNumber = MN.MeterNumber and ReadingDate < M.Month ) ) as [PriorConsumption],
( select Consumption from #MeterReadings where MeterNumber = MN.MeterNumber and ReadingDate =
( select Max( ReadingDate ) from #MeterReadings where MeterNumber = MN.MeterNumber and ReadingDate < M.Month ) ) * 1.15 as [PriorConsumptionPlus15Percent]
from Months as M cross join
MeterNumbers as MN left outer join
#MeterReadings as MR on MR.MeterNumber = MN.MeterNumber and DateAdd( dd, 1 - DatePart( dd, MR.ReadingDate ), MR.ReadingDate ) = M.Month
order by M.Month, MN.MeterNumber