Sergey,
it has the exact same result. I also tried FORCE and SET OPTIMIZE ON. I still takes about 15 seconds to run and sys(3054) says no optimization. I even put a wait window in just before the SQL to make sure it is running the intended code.
John.

>Try

>  update ivinvt
>    set allocated = allocated + c_chng.chng
>  from ivinvt
>    JOIN c_chng
>      ON ivinvt.k_ivinvt = c_chng.k_ivinvt
>

>
>>I am having a problem with the SQL Update below. From the amount of time it takes to run with only 1 or 2 records in the cursor c_chng I believe it is ignoring the index on k_ivinvt and scanning all 186K recs in the inventory table IVINVT. The last time I had this problem was on updating invoice lines and I fixed it by adding a 2nd line to the where clause to include the invoice key. This time there is no other index I can use. The two tables are tied only by the ivinvt.k_ivinvt = c_chng.k_ivinvt. This has got to be a really common event so I know I am missing something here.
>>
>>I added set enginebehavior 90 but it made no difference
>>
>>

set enginebehavior 90
>>
>>* Update inventory allocated amounts
>>TEXT TO mSqlCommand noshow pretext 15
>>  update ivinvt
>>  set allocated = allocated + c_chng.chng
>>  from c_chng
>>  where ivinvt.k_ivinvt = c_chng.k_ivinvt
>>ENDTEXT
>>&mSqlCommand