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simplify query (update with a inner query join)

anushahanna
anushahanna asked
on
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Last Modified: 2021-04-21
i have a update using an inner query..

could you make this  more efficient in TSQL?

this may update 100k records at a time.

thanks
/*
INNER QUERY
select distinct a.abc,b.xyz from tbladult a,table_two b
where a.keyPK = b.keyFK and a.abc is not null and b.xyz is not null
*/

update a 
set abc = b.abc
from table_one a
join 
(
/*
INNER QUERY
*/
select distinct a.abc,b.xyz from tbladult a,table_two b
where a.keyPK = b.keyFK and a.abc is not null and b.xyz is not null
)b
on a.xyz = b.xyz and a.abc is null

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