Sql-server – How to calculate total time taken

So this isn't a great answer, this is kind of a starting answer for somebody else to take on and refine this better. But I'll make a stab at it.

First I have a question: Are you trying to retain this in a view? I don't think you can for what you're wanting to do, it's kinda complicated, so let's examine the operations that you need to do to actually do what you want.

You stated that you want the first 12 rows to be static every time, and they should always have their last column set as NULL, and the others should retain their value. So that's a business rule that we need to encode in SQL. But before we encode this as a rule, let's ask if there's a way to ENSURE that those 12 rows are the RIGHT rows every time. If we can make that assumption, then we can do this as part of the next step.

You're next requirement is to do a calculation on each row with the previous row. Since the first 12 rows are static (and I presume not calculated) then we don't have to ask "what about the first row". So the easiest way to do calculations on the previous row is to assign a rownum to each row, then use the rownum ID in a comparison. This meshes with the previous requirement.

So we should start by doing our select and assigning a rownum as well, like this:

SELECT     
    ROW_NUMBER() OVER (ORDER BY in.I_Date) AS rownum,
    in.I_Date  ,--Date
    in.I_O_P   ,--Money
    in.I_O_H   ,--Money
    in.I_O_L   ,--Money
    in.I_C_O   ,--Money 
    c.AMPS12_C  --Money
    CAST(0.0 AS Money) AS C12WR
FROM
    dbo.IC_Raw_In in
INNER JOIN 
    dbo.AMPS12_C c ON in.I_Serial = c.i_serial

But for the way I would do this, I would funnel these values into a temp table, and then use that to work out what I need. That way you can just refer to the columns in subsequent calls, like this:

UPDATE t 
SET C12WR = NULL
FROM temptable t
WHERE t.rownum < 12 -- see how we set the values = null here?

UPDATE t 
SET C12WR = 510.3958
FROM temptable t
WHERE t.rownum = 12 -- see how we set the value to something static? 
                    -- If this were a stored procedure we could use a value passed in here

and then we continue with:

UPDATE t 
SET C12WR = ( ( t2.C12WR * 11.0 ) + t.I_C_O ) / 12.0
FROM temptable t
INNER JOIN temptable t2 ON t.rownum = (t2.rownum - 1) -- this let's us get the previous row
WHERE t.rownum > 12

Using this logic: After the 13th row, the C12WR column = (prevrow.C12WR * 11 + currow.I_C_O Column) / 12

And then you would just return the values that you wanted from the temptable.

Notice: the things I left off. I did not define the temp table, I did not get rid of the temptable. I did not use appropriate syntax for the temptable addressing. I did not validate anything. I presumed that this was going to be used in a stored procedure. I did not illustrate how to use the static value as a stored procedure passed parameter.

Hope this helps. Hope someone else helps make this a better answer ;)

What you're looking for is Dynamic SQL Pivots. A PIVOT will turn row values into columns based on an aggregate, however you need to define the column names as part of the PIVOT, luckily we can do that on the fly with dynamic SQL. The following should generate the result set you want for a particular company (replace rowValues with your table name):

DECLARE @SQL NVARCHAR(MAX)
DECLARE @Columns NVARCHAR(MAX)
DECLARE @Company NVARCHAR(5) = '01'

SET @Columns = STUFF( (SELECT ',['+H.description+']' AS [data()] 
                        FROM dbo.Headers H
                        WHERE H.company = @Company  
                        ORDER BY H.fieldNumber
                        FOR XML PATH('')),1,1,'')

SET @SQL = '
SELECT company,jobNumber,'+@Columns+'
FROM
(
    SELECT h.company,RV.jobNumber,RV.information,h.description
    FROM Headers h
            INNER JOIN dbo.RowValues RV
                ON RV.fieldNumber = h.fieldNumber
                   AND RV.company = h.company
    WHERE h.company = '+@Company+'  
) as Data
PIVOT
(
    MAX(information) FOR [description] IN ('+@Columns+')
) as p
ORDER BY jobNumber ASC'

EXEC sp_executesql @sql;

Unfortunately due to the possibility that different companies will have different columns there is no reliable way to combine all the the possible sets the above query could generate. Depending on how you want to use this query the easy option is to loop through all the companies and call an SP that contains the above, allowing you to output each company as a separate SELECT. Or you can do something with your SSIS package to output each one into a file.

If you want to insert the data into a table matching the calculated schema you can do a SELECT INSERT and a bit more dynamic SQL to get the data where it needs to go.