Question

I have never seen this before, the rows will be sequential but I have noticed that it skipped over a particular “ID”…. 1 2 3 4 6 7 8… missing 5…

There are no transactions in the INSERT stored procedure so nothing to roll back
We do not allow the deletion of records.

What else can be the case?

Answer 1

Probably a failed insert due to some other unique constraint on the table or a foreign key reference in the table and you try to insert an invalid fk value.

The insert doesn’t have to be in a transaction.

The identity value increments even on a failed insert.

Igor mentions an important point about identities and transactions. From the docs:

Failed statements and transactions can
change the current identity for a
table and create gaps in the identity
column values. The identity value is
never rolled back even though the
transaction that tried to insert the
value into the table is not committed.
For example, if an INSERT statement
fails because of an IGNORE_DUP_KEY
violation, the current identity value
for the table is still incremented.