I'm doing this query

```
Select id, name, (select quantity, PriceBookEntry.Name from OpportunityLineItems where quantity  != NULL)  from Opportunity where StageName = 'Closed Won'

```

And it'll return a bunch of `Opportunities`, but for some of them, `OpportunityLineItems` will be null.

How can I only return the `Opportunities` that have `OpportunityLineItems`?

Doing `and OpportunityLineItems != NULL` makes the query crash with 

```
Invalid Field [object Object]: where StageName = 'Closed Won' and OpportunityLineItems != NULL ^ ERROR at Row:1:Column:158 No such column 'OpportunityLineItems' on entity 'Opportunity'. If you are attempting to use a custom field, be sure to append the '__c' after the custom field name. Please reference your WSDL or the describe call for the appropriate names.

```