Determine record exist by exception of SQL is Principles?

I have a table with primary key and I want to insert new record to that.

In my code, I check if record exists by exception. In the SQL stored procedure, I have insert code and surround by exception, in my application I execute that stored procedure and want to insert new record, if my record exist in table, insert code throws an error:

The INSERT statement conflicted with the FOREIGN KEY constraint “FK_Sup_Item_Sup_Item_Cat”. The conflict occurred in database test, table test. The statement has been terminated.

and goes to the catch block.

In my application I check the error that was returned by SQL, and it shows a message box to user that record is exist.

I want to know, is this way is Principles? or I must use if exist statement in SQL?

Answer

Exception should never be used when you can avoid it and return a value.
Exception is a “stress” on a system and much slower than any other way.

Its customary for a SP to return 0 if everything is Ok and a negative value if there is an error.
Either check your SP return code in application or use out parameter to determine problem. An error should be truly an error.