--- Jim Dodgen <[EMAIL PROTECTED]> wrote:

> this should work.
> 
> UPDATE T1
> SET T1.colA = (select T2.colA from T2 where T1.colC
> = T2.colC),
>     T1.colB = (select T2.colB from T2 where T1.colC
> = T2.colC)
> WHERE EXISTS (select * from T2 where T1.colC =
> T2.colC);
> 

Jim,

Thanks for your answer.  Indeed, it works great.  

I checked the statement with EXPLAIN but as I am new
to SQLite, did not make much sense of the plan. 
However, it seems like the same sub-select gets
executed repeatedly, once for each updated column and
once at the end.  Does this degrade performance or
does the engine optimize these separate statements
into one?  I ask because the file I  need to run this
update statement against has several million records.




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