I have a problem in implementing triggers for conditions as schema of table given ProjectMember (EmpID, FirstName, LastName, IsManager, BudgetAuthority) Project (ProjectID, Title, Start, Deadline, First, Budget, Manager) Task (TaskID, Name, Cost, Project, Assignee) Schedule (Task, Successor) implement triggers in POSTGRESQL for Project.Budget = 1000 * sum (Project.Tasks.Cost) + 10%, { ProjectManager.BudgetAuthority >= sum (ProjectManager.Manages.Budget) }