I have a table of cities like:

```
state  city
-----  ----
texas  houston
texas  austin
texas  dallas
texas  san antonio
texas  beaumont
texas  brownsville
texas  el paso
california  anaheim
california  san diego
california  los angeles
california  oakland
california  simi valley
california  san francisco

```

I need a query to find the states that don't have a city named 'houston' or 'dallas'. My first thought was this

```
select distinct state from cities where city not in ('houston', 'dallas');

```

but that won't work. I think I need a subquery and a NOT IN of some sort..