Does the sequence of Insert/Update matter?

Question

Dear friends
I wanted to know whether there is any difference in results if I change the sequence of Insert/Update statements. For example, if I'm inserting / updating records in a table, normally I write my code as below
<code>
Begin
Insert Into Table Name(...)
Values(...);
Exception
When Dup_Val_On_Index Then
Update Table Name Set
Column_Name = Value;
When Others Then
Sqlerrm;
End;
</code>
Lets assume, if I change the order of statements as below:
<code>
Begin
Update Table Name Set
Column_Name = Value;
If Sql%NotFound Then
Begin
Insert Into Table Name(...)
Values(...);
End;
Exception
When Others Then
Sqlerrm;
End;
</code>
So does this change make any difference in net results?

Answer 1

Yes...till before today morning, it had no difference to me too, but today I was facing an insertion problem in a procedure in which insert statement had to go into when_dup_val exception part after first record and execute update statement. But surprisingly, it was going into when_dup_val only for 2nd record, i.e. 1st record was inserted as new record, then 2nd record had same primary key values, so when_dup_val caused to execute update statement, and lastly for 3rd record, having same primary key values, instead of executing update statement, insertion was going into when_others exception part and raising error ORA-01008.
After very detailed hit n trial, I just reversed the operations, took udpate statement before insert in my code and then all the things got right. Procedure is executing finely.
Although I've resolved the issue but I couldn't digest this change, thats why asking you peeps the operations behind.