Editing Database trigger (section)

=== Before each - row-level trigger ===
This example demonstrates a BEFORE EACH ROW trigger that modifies the INSERT using a WHEN conditional. If the last name is larger than 10 letters, using the SUBSTR function<ref>{{Cite web|url=https://www.databasestar.com/oracle-sql-functions/|title=Oracle SQL Functions – The Complete List|date=December 26, 2014}}</ref> we change the last_name column value to an abbreviation.

<syntaxhighlight lang="sql">
CREATE OR REPLACE TRIGGER phone_book_insert
  BEFORE INSERT ON phone_book FOR EACH ROW
  WHEN (LENGTH(new.last_name) > 10)
BEGIN
    :new.last_name := SUBSTR(:new.last_name,0,1);
END;
</syntaxhighlight>

Now performing an INSERT of someone with a large name.
<syntaxhighlight lang="sql">
INSERT INTO phone_book VALUES
(6, 'VeryVeryLongLastName', 'Erin', 'Minneapolis', 'MN', '989 University Drive', '123-222-4456', 55408, TO_DATE('11/21/1991', 'MM/DD/YYYY'));
</syntaxhighlight>

{| class="wikitable"
|-
! Person_ID !! Last_Name !! First_Name !! City !! State_Abbreviation !! Address !! Phone_Number !! Zip_code !! DOB
|-
| 6 || V || Erin || Minneapolis || MN || 989 University Drive || 123-222-4456 || 55408 || 21-NOV-91
|}

The trigger worked as per the result above, modifying the value of the INSERT '''before''' it was executed.