diff --git a/database/database_table.py b/database/database_table.py
index db3555f990ef68f10c874c4c4253c0595df989b1..8025b136f5fa834e0f89b90d3a90a2a6fd213665 100644
--- a/database/database_table.py
+++ b/database/database_table.py
@@ -201,11 +201,13 @@ class DatabaseTable(Table):
             bind = self.metadata.bind
 
         pks = get_primary_keys(self)
-        primary_keys = (ttable.columns.get(pk.name) for pk in pks)
 
-        new_pk = PrimaryKeyConstraint(*primary_keys)
-        query = AddConstraint(new_pk)
-        bind.execute(query)
+        if len(pks) > 0:
+            primary_keys = (ttable.columns.get(pk.name) for pk in pks)
+
+            new_pk = PrimaryKeyConstraint(*primary_keys)
+            query = AddConstraint(new_pk)
+            bind.execute(query)
 
     def populate_temporary(self, ttable, in_file, header, year, delimiters=[';', '\\n', '"'],
                            null='', offset=2, bind=None):