1 files changed, 2 insertions, 1 deletions
diff --git a/model.py b/model.py
index 9c04e83..e9ee2be 100644
--- a/model.py
+++ b/model.py
@@ -79,7 +79,7 @@ class ConstExpense (Expense):
     start   = ReqField(T.Date, index = True)
     end     = ReqField(T.Date, index = True)
 
-    prev = ManyToOne('ConstExpense')
+    prev = ManyToOne('ConstExpense', ondelete = "SET NULL")
     next = OneToOne('ConstExpense', inverse = 'prev')
     
     monthly = ColumnProperty(lambda c: sql.cast(c.expense / c.months, ExpNum))
@@ -135,6 +135,7 @@ session = elixir.session
 #
 
 Index('idx_single_date', SingleExpense.year, SingleExpense.month)
+Index('idx_start_end', ConstExpense.start, ConstExpense.end)
 
 if __name__ == "__main__":
     elixir.create_all()