How will the query run faster?

Question

Transact SQL

Hello.
Let's say we have a table. For the example, one bit column is sufficient.
0
0
0
0
1
I need to execute an update query, which will replace all values ​​of 1 with
0
It's just that I imagine an algorithm with a condition like this
iteration of lines
If field = 1 then field = 0
next line
and an algorithm without a condition so
iteration of lines
field = 0
next line
So, which query will run faster? What takes more time, overwriting the value or comparing? After all, if the same amount of time is spent, then in the case of the condition there will be 1 more operation (besides comparison, it will also be overwritten)

Answer 1

It remains only to think about how it will be with the version with the index. :)

Answer 2

Good afternoon.
It will be faster to filter by field, and then update the fields (you need an index by field for good work speed, you need to overlay the field with an index)