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Update A Column based on results of another column

Posted on 2013-11-26
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Last Modified: 2014-05-27
In the same table "PropertyCalcs", I am try to update a column based a minimum value of another column.

I have PropertyID, OrderNumber, and First Inspection Date as columns.

For each ProptertyID, I need SQL to find the min(OrderNumber) and then write 'First Inspection Date' in the First Inspection Date column, when it finds the minimum OrderNumber for that PropertyID.

If you have any questions, please let me know and I'll be happy to answer them.
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Question by:Erik Hauser
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4 Comments
 
LVL 66

Accepted Solution

by:
Jim Horn earned 500 total points
ID: 39678062
Air code.  I also do my own stunts..
UPDATE your_table
SET [First Inspection Date] = 'First Inspection Date'
FROM your_table yt
JOIN (
   SELECT ProptertyID, min(OrderNumber) as min_order_number
   FROM your_table
   GROUP BY PropertyID) yt_min ON yt.PropertyID = yt_min.PropertyID AND yt.OrderNumber = yt_min.min_order_number

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Author Comment

by:Erik Hauser
ID: 39678085
JimHorn,

Thank you so much!  I was practically there in two separate queries and couldn't figure out how to join them.

Thanks, I'll try that!
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LVL 50

Expert Comment

by:Lowfatspread
ID: 39678147
;with cte as (select [first inspection date]
                      ,row_number() over ( partition by propertyid order by ordernumber) as rn
    from propertycalcs)
update  x
   set [first inspection date]='first inspection date'
 from cte as x
where rn=1
 and [first inspection date] <> 'first inspection date'
0
 
LVL 69

Expert Comment

by:Scott Pletcher
ID: 39678594
I'd suggest storing just a bit flag that indicated this: you can translate it to the characters using a computed column.

isFirstInspectionDate bit

update ...
set isFirstInspectionDate = 1
...


ALTER TABLE PropertyCalcs
ADD [First Inspection Date] AS CASE WHEN isFirstInspectionDate = 1 THEN 'First Inspection Date' ELSE '' END
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