Shortage alert?

Question

Database

How to make a notification when a position is selected in the Employee table and if the remainder is < 0, then a message like: "Please, there is no free position" pops up. Well, if the remainder is 0, then if I want to select this position again, then in the form, when choosing, it will select a message from me. And if this position exists, then -1 is subtracted from the number of employees.

Answer 1

Judging by the "trigger" tag, you want to link the number of rows in the Employee table and the "Number_Employees" field in the "Staffing" table through triggers. Hence the solution - create triggers/trigger on the Employee table to control/modify the field Number_of_Employees and triggers on the Staff_schedule table to control the number of entries in the Employee.