Ho to Generate the Numeric Values Automatically before saving the records

Question

Hello to everybody,
I have a data block naming “BILL” consisting of the following 3 field.
1. Sr_No
2. Bill_Amount
3. Description
This Data Block consist 10 records at a time.
I want that whenever I insert records in the above data block.
Serial No should automatically be generated.
For this I have applied the following code in “WHEN-NEW-ITEM-INSTANCE” trigger.
<CODE>
SELECT NVL(MAX(Sr_No),0)+1 INTO :BILL.Sr_No FROM BILL;
</CODE>
Whenever I insert records in the BILL data block, the first row automatically generates the “Sr_No”, but when I move to the next record, (remember currently I have not saved the record), the same value which appeared in the previous record appears in the Sr_No field.
For example, when I insert records for the first time in the BILL, the Sr_No field automatically generates value “1”, but when I move to the next record while not saving the first record the next row still generating value “1”, while it should be value “2” and so on.
Note that I want that before saving the previous record when I move to the next row, the Sr_No should generate the next continuous value like in example.
Please help me to solve out this problem.

Answer 1

You have practically scratched you left ear with your right foot while jumping on the left foot :-)
Seriously, you guys don't need to go to all this trouble.
If you want a serial number incrementation, all you need to do is to either select the max value + 1 from the table or select the next value from a sequence in an PRE-INSERT trigger on block level, and that's it!!!!
Tony