Question

I’m trying to access multiple tables as a single view but I’m not matching any data in my queries. I am fairly certain that the problem lies in the view declaration.

CREATE VIEW IF NOT EXISTS method_view 
AS SELECT 
 peercreateddata.id,
 peercreateddata.name,
 peercreateddata.shared,
 peercreateddata.authorHash,
 peercreateddata.creationDate,
 peercreateddata.firstSeen,
 peercreateddata.lang,
 methods.primaryMatch,
 methods.methodHash,
 methods.methodbyline,
 methods.methodexpirationDate,
 methods.methodlocation,
 localResources.localmimeType,
 remoteResources.remotemimeType,
 remoteResources.remotelocation 

FROM peercreateddata peercreateddata,
 methods methods,
 localResources localResources,
 remoteResources remoteResources 

WHERE (methods.peerDataId = peercreateddata.id) 
      AND (localResources.localMethodId = methods.id) 
      AND (remoteResources.remoteMethodId = methods.id) ;

Looking at the WHERE clause, methods.peerDataId always matches a single value of peercreateddata.id. The tables localResources and remoteResources are sometimes empty, sometimes do not contain matches to the query, and sometimes contain multiple matches.

I am developing for Android. The syntax passes a validator (although some complaints about using a field called ‘name’).

Answer 1

Use inner and outer join clauses. See the docs.

Replace your from clause with this and get rid of the where

FROM peercreateddata peercreateddata
 inner join methods methods 
       on methods.peerDataId = peercreateddata.id
 left outer join localResources localResources 
       on localResources.localMethodId = methods.id
 left outer join remoteResources remoteResources 
       on  remoteResources.remoteMethodId = methods.id