After insert trigger doesn't work when using Inserted - sql-server

Question

I'm trying to write a trigger on my Employees table that should not allow the insertion of a new employee that has a hire date that is older than the hire date of his boss
CREATE TABLE [dbo].[Employees]
(
[EID] [int] IDENTITY(1,1) NOT NULL,
[Ename] [nvarchar](20) NOT NULL,
[Gender] [nvarchar](1) NOT NULL,
[IsMarried] [nvarchar](1) NOT NULL,
[Birthdate] [date] NOT NULL,
[HireDate] [date] NOT NULL,
[Salary] [float] NOT NULL,
[Notes] [nvarchar](200) NULL,
[NationalityID] [int] NULL,
[BossID] [int] NULL,
CONSTRAINT [PK_Employees]
PRIMARY KEY CLUSTERED ()
)
And here's the trigger code:
CREATE TRIGGER [dbo].[Trig_04]
ON [dbo].[Employees]
AFTER INSERT
AS
BEGIN
IF ((SELECT INSERTED.HireDate FROM INSERTED WHERE BossID <> EID) <
(SELECT Employees.HireDate FROM Employees
WHERE EID IN (SELECT Employees.BossID FROM Employees WHERE BossID <> EID)))
ROLLBACK
END
It executes normally (no errors) but it just doesn't work, but when I was using the employees table in the subquery instead of the inserted table, it was working normally. Does anyone have an answer for this?

Answer 1

You have to write triggers in SQL Server to handle the fact that INSERTED could contain multiple records. You cannot assume it will only be a single record. I think the following is what you are looking for:
if exists (
select 1
from Inserted I
where I.BossID <> I.EID
and I.HireDate < (select E.HireDate from Employees E where E.EID = I.BossID)
) begin
ROLLBACK;
end