ZendFramework 2:Syntax error or access violation: 1066 Not unique table/alias: - zend-db

Question

I am a new at Zendframework 2. I am trying to join two tables and display the result.
The two tables are.
Works and Artist . The tables are joined based on artist_id.
STEP 1> Created 2 class(Works , Artist) in Model
STEP 2> In WorksTable I have the following code
class WorksTable extends AbstractTableGateway
{
protected $table ='works';
public function __construct(Adapter $adapter)
{
$this->adapter = $adapter;
$this->resultSetPrototype = new HydratingResultSet(
new ArraySerializableHydrator(),
new Works()
);
$this->resultSetPrototype->buffer();
$this->initialize();
}
public function fetchAll()
{
$select = $this->getSql()->select();
$select->join('works','artists.artist_id = artist_id ');
//create paginator object to display records
$paginator = new Paginator(
new DbSelect($select, $this->adapter, $this->resultSetPrototype)
);
return $paginator;
}
}
STEP 3> In controller I defined the following code
public function searchAction()
{
$request = $this->getRequest();
$paginator = $this->getWorksTable()->fetchAll();
// $paginator->setItemCountPerPage(12);
$vm = new ViewModel(array(
'poster' => $paginator,
));
$vm->setVariable('paginator', $paginator);
return $vm;
}
For statement $paginator->setItemCountPerPage(12); get error
Message:
SQLSTATE[42000]: Syntax error or access violation: 1066 Not unique table/alias: 'works'
Has anyone come across this error? Any ideas on how to resolve this?

Answer 1

you join works table to itself, mysql treat it as two separate tables joined but with same name, hence the error.
Use alias for table you join:
$select = $this->getSql()->select();
$select->join(array('w' => 'works'),'artists.artist_id = artist_id ');
but it looks like it is just typo there and table should be artists

Answer 2

There hasn't used artists table begin the query.and also didn't use works table on join.
use Zend\Paginator\Adapter\DbSelect;
use Zend\Db\Sql\Sql;
public function fetchAll()
{
$sql = new Sql($this->tableGateway->getAdapter());
$select = new Select();
$select->from("artists");
$select->columns(array('*'));
$select->join('works','artists.artist_id = works.artist_id',array('your_wanted_column_names,don't mention again artist_id here because there should be a error'));
$paginator = new Paginator(
new DbSelect($select, $this->adapter, $this->resultSetPrototype)
);
return $paginator;