private function getRevisionId()
 {
     if ($this->revisionId === null) {
         $date = date_create("now")->format($this->platform->getDateTimeFormatString());
         if ($this->config->getCurrentUser() != null) {
             $userId = $this->config->getCurrentUser()->getId();
         } else {
             $userId = null;
         }
         $this->conn->insert($this->config->getRevisionTableName(), array('timestamp' => $date, 'user_id' => $userId, 'note' => $this->config->getNote(), 'ipaddress' => $this->config->getIpAddress()));
         $sequenceName = $this->platform->supportsSequences() ? 'REVISIONS_ID_SEQ' : null;
         $this->revisionId = $this->conn->lastInsertId($sequenceName);
     }
     return $this->revisionId;
 }
 /**
  * Get the SQL Statements to drop the given schema from underlying db.
  *
  * @param Schema $dropSchema
  * @return array
  */
 public function getDropSchema(Schema $dropSchema)
 {
     $visitor = new DropSchemaSqlCollector($this->platform);
     $sm = $this->conn->getSchemaManager();
     $fullSchema = $sm->createSchema();
     foreach ($fullSchema->getTables() as $table) {
         if ($dropSchema->hasTable($table->getName())) {
             $visitor->acceptTable($table);
         }
         foreach ($table->getForeignKeys() as $foreignKey) {
             if (!$dropSchema->hasTable($table->getName())) {
                 continue;
             }
             if (!$dropSchema->hasTable($foreignKey->getForeignTableName())) {
                 continue;
             }
             $visitor->acceptForeignKey($table, $foreignKey);
         }
     }
     if (!$this->platform->supportsSequences()) {
         return $visitor->getQueries();
     }
     foreach ($dropSchema->getSequences() as $sequence) {
         $visitor->acceptSequence($sequence);
     }
     foreach ($dropSchema->getTables() as $table) {
         /* @var $sequence Table */
         if (!$table->hasPrimaryKey()) {
             continue;
         }
         $columns = $table->getPrimaryKey()->getColumns();
         if (count($columns) > 1) {
             continue;
         }
         $checkSequence = $table->getName() . "_" . $columns[0] . "_seq";
         if ($fullSchema->hasSequence($checkSequence)) {
             $visitor->acceptSequence($fullSchema->getSequence($checkSequence));
         }
     }
     return $visitor->getQueries();
 }