[Existe Algo de Errado Neste Código?]

Você me diga. O que acontece quando você roda o programa?

Coloque seu código dentro do bloco de códigos. Edita e bota dentro do <> (code)

[Erro ao trazer hora]

Cara, nem li isso aí tudo. Ajeita teu post colocando o código dentro do bloco específico. Edita aí e aperta o botão que tem um símbolo de maior e menor em azul.

<>

[Popular uma combobox com valores de uma coluna SQL]

Fala amigo!

Tenha cuidado aqui com a forma de conexão, até porque você não está vendo minha classe ConexaoBD. Mas como o seu problema é popular a combo, imagino que conexão com o banco você já tenha.

Faz um select aí como tu sempre faz. E pra popular a combobox, usa um while pra adicionar items.

private void populateCombo(){
        try{
            Connection con = ConexaoBD.createConnection();
            String sql = "SELECT * FROM \"alunos\" ORDER BY \"nome\"";
            PreparedStatement stm = con.prepareStatement(sql);
            ResultSet rs = stm.executeQuery();
            
            while(rs.next()){
                String name = rs.getString("nome");
                jComboBox1.addItem(name);
            }
        }catch(Exception e){
            JOptionPane.showMessageDialog(null, e);
        }
    }

[JTable and Postgres cross-reference problem]

Hello, I´ve created a JForm (GUI) and added a JTable to it. Then right clicked the table and 'bind' -> 'elements'. So I imported the table I want from my database and the communication worked because the column names are now displayed on the table header.

But when I run the program, it gives the following error:

Internal Exception: org.postgresql.util.PSQLException: ERROR: cross-database references are not implemented: "cambio.publico.teste"
Call: SELECT COD, NOME, TELEFONE FROM CAMBIO.publico.teste
  Posição: 33
Query: ReadAllQuery(referenceClass=Teste sql="SELECT COD, NOME, TELEFONE FROM CAMBIO.publico.teste")
Error Code: 0
Call: SELECT COD, NOME, TELEFONE FROM CAMBIO.publico.teste
Query: ReadAllQuery(referenceClass=Teste sql="SELECT COD, NOME, TELEFONE FROM CAMBIO.publico.teste")
at org.eclipse.persistence.internal.jpa.QueryImpl.getDetailedException(QueryImpl.java:378)
at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:260)
at org.eclipse.persistence.internal.jpa.QueryImpl.getResultList(QueryImpl.java:469)
at visao.TelaCaixa7.initComponents(TelaCaixa7.java:33)
at visao.TelaCaixa7.<init>(TelaCaixa7.java:18)
at visao.TelaCaixa7$1.run(TelaCaixa7.java:106)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:749)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:702)
at java.awt.EventQueue$3.run(EventQueue.java:696)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:719)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Caused by: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: org.postgresql.util.PSQLException: ERROR: cross-database references are not implemented: "cambio.publico.teste"
  Posição: 33
Error Code: 0
Call: SELECT COD, NOME, TELEFONE FROM CAMBIO.publico.teste
Query: ReadAllQuery(referenceClass=Teste sql="SELECT COD, NOME, TELEFONE FROM CAMBIO.publico.teste")
at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:340)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:682)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:558)
at org.eclipse.persistence.internal.sessions.AbstractSession.basicExecuteCall(AbstractSession.java:2002)
at org.eclipse.persistence.sessions.server.ServerSession.executeCall(ServerSession.java:570)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:242)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:228)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeSelectCall(DatasourceCallQueryMechanism.java:299)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.selectAllRows(DatasourceCallQueryMechanism.java:694)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRowsFromTable(ExpressionQueryMechanism.java:2738)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRows(ExpressionQueryMechanism.java:2691)
at org.eclipse.persistence.queries.ReadAllQuery.executeObjectLevelReadQuery(ReadAllQuery.java:495)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeDatabaseQuery(ObjectLevelReadQuery.java:1168)
at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:899)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1127)
at org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:403)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:1215)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2896)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1804)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1786)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1751)
at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:258)
... 18 more
Caused by: org.postgresql.util.PSQLException: ERROR: cross-database references are not implemented: "cambio.publico.teste"
  Posição: 33
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2270)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1998)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:570)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:420)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:305)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeSelect(DatabaseAccessor.java:1007)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:642)
... 38 more

I believe the problem is because the jtable can be edited and said editions are automaticaly recorded on the database table which it is not allowing.

Is there a way to explicitly tell my postgres table to allow cross-reference?

Also I may be way off and the root cause be something else entirely. Thanks for the help.