I've got a table with data named energydata
it has just three columns
(webmeterID, DateTime, kWh)
I have a new set of updated data in a table temp_energydata
.
The DateTime
and the webmeterID
stay the same. But the kWh
values need updating from temp_energydata
table.
How do I write the T-SQL for this the correct way?
This question is related to
sql-server-2008
tsql
UPDATE ed
SET ed.kWh = ted.kWh
FROM energydata ed
INNER JOIN temp_energydata ted ON ted.webmeterID = ed.webmeterID
Update energydata set energydata.kWh = temp.kWh
where energydata.webmeterID = (select webmeterID from temp_energydata as temp)
I often used Bacon Bits great answer as I just can not memorize the syntax.
But I usually add a CTE as an addition to make the DELETE part more useful because very often you will want to apply the merge only to a part of the target table.
WITH target as (
SELECT * FROM dbo.energydate WHERE DateTime > GETDATE()
)
MERGE INTO target WITH (HOLDLOCK)
USING dbo.temp_energydata AS source
ON target.webmeterID = source.webmeterID
AND target.DateTime = source.DateTime
WHEN MATCHED THEN
UPDATE SET target.kWh = source.kWh
WHEN NOT MATCHED BY TARGET THEN
INSERT (webmeterID, DateTime, kWh)
VALUES (source.webmeterID, source.DateTime, source.kWh)
WHEN NOT MATCHED BY SOURCE THEN
DELETE
If you need just update your records in energydata
based on data in temp_energydata
, assuming that temp_enerydata
doesn't contain any new records, then try this:
UPDATE e SET e.kWh = t.kWh
FROM energydata e INNER JOIN
temp_energydata t ON e.webmeterID = t.webmeterID AND
e.DateTime = t.DateTime
Here is working sqlfiddle
But if temp_energydata
contains new records and you need to insert it to energydata
preferably with one statement then you should definitely go with the answer that Bacon Bits gave.
THE CORRECT WAY IS :
UPDATE test1
INNER JOIN test2 ON (test1.id = test2.id)
SET test1.data = test2.data
Source: Stackoverflow.com