ohhh I got it. Thanks to the added constraint I found out I already had duplicates in the table.
Much obliged. Thank you.

Though I appreciate your opinions can somebody actually tell me on how to accomplish this ?

but if I add unique index to a  field am I not going to stop insertion of other employees  ?
Its 3 conditions that have to be applied in order...

this is sql server 2014 and those are parameters I supply within my application.

DECLARE
@OD DATETIME,
@DO  DATETIME,
@TipSobe VARCHAR(6),
@KodaCenika  INT,
@Sezona   INT,

@p1 DATETIME,
@p2 DATETIME,
@p3 VARCHAR(6),
@p4 INT

SELECT
@Od = @p1, @Do = @p2,...

You dont get anything free.
For the SQL databases you still need to pay like everyone else.

On the bottom, Azure is too expensive.
If you have many user...

There is no Free Visual studio subscription. What are you talking about ?

Wow, Thom....wonderful ..
What if I have the case when numbers and letters are separated like : 1 A   ?
Right now, when I tested  , soon as I add...