このトリガーをExpenseTableに追加します
CREATE TRIGGER ExpenseSum AFTER INSERT ON ExpenseTable FOR EACH ROW
BEGIN
UPDATE ProjectsTable P
SET ExpenseTotal =
(SELECT SUM(ExpenseAmount) from ExpenseTable
where ExpenseTable.ProjectID= P.ProjectID)
where P.ProjectID = New.ProjectID;
END
トリガーを追加することを忘れないでくださいAfter Update
およびAfter Delete
ExpenseTotalを更新するには