datastax Java驱动程序选择+

Question

Can I select and distinct in one query?

For example:

QueryBuilder
      .select()
      .all()
      .from(Connector.KEY_SPACE_NAME, table)
      .where(eq(this.uuidHotel, hotelUUID))
      .discardAll(this.uuidHotel, javaList)

Answer 1

I cannot understand your column family structure. But your operation seems unusual.

You are querying for a field called uuidHotel , so I assume you are querying for UUID type in C*. It has to be the partition key, else you can't expect a result.

But you are also using discardAll on the same field. It can only be used on CollectionType fields. https://docs.datastax.com/en/cql/3.0/cql/cql_using/use_collections_c.html

So it is unusual.

I think you are looking for is DISTINCT . Please refer to http://docs.datastax.com/en/cql/3.1/cql/cql_reference/select_r.html

Hope it helps!