Two foreign keys referencing the same primary key

Question

Is this okay to have two foreign keys in one table referencing one primary key of other table?

EmployeeID is a primary key in the employee table and appearing as a f

Answer 1

I would go with option 1. It is perfectly fine to have two foreign key columns referencing the same primary key column in a different table since each foreign key value will reference a different record in the related table.

I'm sure option 2 would work, but you would essentially have a 1-to-1 relationship between TIMESHEET_TABLE and TIMESHEET_FILLED_BY, making two tables unnecessary and more difficult to maintain.

In fact, if both ENTERED_BY and TIMESHEET_FOR are required in pairs, using option 1 makes far more sense because this is automatically enforced by the database and foreign keys.

Answer 2

yes, there is no problem with that...you can use a primary key of one table in other table as foreign key two times.

Answer 3

Option 1 is a perfect solution. You may define foreign key constraint as following

1st foreign key constraint for Timesheet_For column

ALTER TABLE TIMESHEETTABLE 
ADD CONSTRAINT fk_TimesheetTable_EmployeeTable
FOREIGN KEY (TIMESHEET_FOR)
REFERENCES EMPLOYEETABLE(EMPLOYEE_ID)

2nd foreign key constraint for Entered_By column

ALTER TABLE TIMESHEETTABLE 
ADD CONSTRAINT fk_TimesheetTable_EmployeeTable_1
FOREIGN KEY (ENTERED_BY)
REFERENCES EMPLOYEETABLE(EMPLOYEE_ID)

Answer 4

Your query like :

SELECT t.EMPLOYEE_ID, a.NAME as TimeSheetFor, b.NAME as EnteredBy 
FROM timesheet t
JOIN employee a ON t.timesheet_for =a.employee_id
JOIN employee b ON t.entered_by = b.employee_id

Using this query you will get result as you want.