Count (*) (asterisk) on Querydsl / MySQL?

The original MySQL functional query that lists all and only vendors that have all of the listed tags:

SELECT * FROM provider
  INNER JOIN provider_tag
  ON provider_tag.provider_id = provider.id AND provider_tag.tag_id in (1, 2)
  GROUP BY (provider.id)
  HAVING COUNT(*) = 2

      

        
        
        
      

    

Translating to MySQLQuery to Querydsl is easy ...

MySQLQuery query = new MySQLQuery(conn, dialect);

List<Integer> tagIds = ...;

query.from(provider)
    .innerJoin(provider_tag)
    .on(providerTag.providerId.eq(provider.id), providerTag.tagId.in(tagIds))
    .groupBy(provider.id)
    .having(???);

      

        
        
        
      

    

... except for clause c having

.

How to add COUNT(*)

to the request?

EDIT after Timo 1's fix suggestion :

So the request looks like this:

SearchResults<Tuple> result = query.from(provider)
    .innerJoin(providerTag)
    .on(providerTag.providerId.eq(provider.id), providerTag.tagId.in(tagIds))
    .groupBy(provider.id)
    .having(Wildcard.count.eq((long) tagIds.size()))
    .listResults(
        provider.id,
        provider.name);

      

        
        
        
      

    

However, this throws an SQLException Illegal operation on empty result set

if the result set is empty.

My other queries that return an empty result set don't throw exceptions, so I guess I wouldn't need to catch the exception, but is there a problem that needs to be fixed?

The generated MySQL works fine (returns 0 rows) so there is no problem there.

EDIT 2 :

The problem was groupBy()

. This seems to work if you apply the correction shown in the issue .