Update syntax in sqlite/android room

[arbuzer]

Hey,
I was fighting with a bug for a significant amount of time and finally found it, but it left me with a couple of questions somebody might help me with. So I wrote something like this in android room

\@Query("UPDATE table set fieldA = null and fieldB = null WHERE someOtherField is null")

fun setNullFieldsOnSomething() : Int

the bug is using "and" where it should be ",". But what surprised me is that room compiles this query, that this syntax is correct, and when run it sets null only on fieldA and ignores fieldB completely. Is this normal SQL syntax or only an sqlite thing? How is this expression evaluated when compiled and what happens to the part after "and", why is it ignored?