Sequence and insert failure

Question

In a PRE-INSERT trigger, I query my sequence in order to increment my id :
SELECT seq_DocVente.NEXTVAL into :NEW.Code FROM dual;
But when my insertion fails due to a unique constraint (for sample), I loose a value because my sequence is queried but my record not inserted.
Is there a way to prevent this problem ?

Answer 1

Hellow PERRET,
There is a better approach you can follow by Placing the code on a database trigger.
First: Create a Function Called
Get_Seq_Id
like this:
Function Get_Seq_ID Returns NUMBER
IS
Seq NUMBER;
Begin
SELECT seq_DocVente.NEXTVAL
into Seq
FROM dual;
Return Seq;
End Get_Seq_ID;
At this Moment you may do one of the following:
1-Place the Code:
:New.Code in "When-Create-Record"
and not pre-insert ...
2-Or Place it in a DB Trigger:
(And this is better)
Cut this function and then paste it into Stored Procedure node under Database Objects, and then under ur Schema.
Do The Following:
Go to
Database Objects -> schema Name -> Tables ->
Table Name.
double Click on Triggers Node.
you will create a databse Trigger:
1-Click New
2-Choose Triggering: "Before"
3-Then chose "insert" as a Statement.
4-For each - > choose "Row"
in Trigger Body write the folowing
:New.ID := Get_Seq_ID;
click save.
You will see if trigger has been compiled successfully.
To Adjust This Trigger for High Performance, Write the following in the above "When" Box:
New.ID IS NULL.
This Will Prevent concurrent users from inserting any value unless ID IS Null.
Hope This Helps.
Regards,
Tariq
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