February 25, 2013 at 1:10 pm
I am having a problem, but think I may be making it harder on myself. I need to update a table with new estimates. However, the table to be updated has a column for "benchmarking" data (In 1980, data = 42, in 1985 = 45, etc.). This benchmarking column was well intentioned, but not maintained well and has become useless, basically. But that does mean I want to delete old benchmarks.
So, I need to update the table, but only want the latest benchmark date to be updated. Here is an example of data:
areayear benchmarkNbrEmployed
01976 1980 1758544
01976 2005 1804304 <<This is the row to update.
Now, I know if I just want a result set, I can use the query:
SELECT
,[year],MAX([benchmark]),MIN([NbrEmployed])
FROM Table
WHERE year = '1976'
GROUP BY area, year
However, I don't see how this would work using an UPDATE or MERGE query. Does anyone have any ideas? Thank you -- Amy
February 25, 2013 at 2:58 pm
Hi,
i think the following statement would help.
update t
from Table t
inner join (
select area,
[year],
max(benchmark) benchmark,
NbrEmployed
from Table
group by
area,
[year],
NbrEmployed
) x on t.area=x.area
and t.[year]=x.[year]
and t.benchmark=x.benchmark
and t.NbrEmployed
[font="Arial"]Kind regards,
Patrick Fiedler
Consultant
February 25, 2013 at 3:01 pm
Not a lot to go on, but maybe something like this:
DECLARE @rows_updated TABLE (
area <same_datatype_as_in_table>,
year <same_datatype_as_in_table>,
benchmark <same_datatype_as_in_table>
)
UPDATE tn
SET
<column_name> = <new_value>
OUTPUT
INSERTED.area, INSERTED.year, INSERTED.benchmark INTO @rows_updated
FROM dbo.tablename tn
INNER JOIN (
SELECT
, [year],
MAX([benchmark]) AS [benchmark],
MIN([NbrEmployed]) AS [NbrEmployed]
FROM dbo.tablename
WHERE year = '1976'
GROUP BY
area, year
) AS matching_rows ON
matching_rows.area = tn.area AND
matching_rows.year = tn.year AND
matching_rows.benchmark = tn.benchmark
SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.
February 25, 2013 at 4:49 pm
Amy.G (2/25/2013)
...Now, I know if I just want a result set, I can use the query...
If you can produce the result set then all you can can produce an update statement using a CTE like so:
-- Sample data
DECLARE @testData TABLE (id int identity primary key, txt1 varchar(10), yr int, updateme varchar(20));
DECLARE@old varchar(10)='old data';
INSERT INTO @testData VALUES ('xxx',1999,@old), ('xxx',1998,@old), ('yyy',1995,@old), ('xyz',1998,@old);
--Before
SELECT * FROM @testData
-- Update using a CTE
;WITH IDs AS
(SELECT txt1, MAX(yr) AS yr
FROM @testData
GROUP BY txt1 ),
UpdateThis AS
(SELECT updateme
FROM @testData td
JOIN IDs x ON td.txt1=x.txt1 AND td.yr=x.yr
)
UPDATE UpdateThis
SET updateme='new estimate';
--After
SELECT * FROM @testData
-- Itzik Ben-Gan 2001
February 26, 2013 at 10:30 am
Alan.B. -- not only did it work, but I learned something completely new. Thank you.
Amy
February 28, 2013 at 8:21 am
No problem Amy.
That's actually a newer technique for me too and has been very helpful. You can do deletes in the same way...
;WITH X AS (SELECT * FROM dbo.emp WHERE active=0)
DELETE FROM X
-- Itzik Ben-Gan 2001
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