How sql server updates data in batches.

Update? Table name? Settings? Value = case? What time? id= 1? then what A kind of values

What time? id=2? then what A value?

What time? id=3? then what A value? Or what? Value?

Take the example of end above as an example, which means that when id= 1, set a value for value, when id=2, set another value for value, and so on. Keep the original value without changing it, and end with end.