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Difference within a field between records

From: John Eggert <eggert_at_sympatico.ca>
Date: Sun, 20 Jan 2002 14:54:41 -0500
Message-ID: <3C4B2081.16099320_at_sympatico.ca> 





Hi:



Is this as hard as it seems?



Table:


weekID     tankID     Mass
1          1          150
2          1          250
  




Calculate the increase in mass in tank 1 over the week (in this case 250
- 150 = 100). Call this production. Production will be reported. Weekly
production over the previous n years will be used as input for
statistical analysis.



Thanks



JE
Received on Sun Jan 20 2002 - 20:54:41 CET












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