Check and change new value in a before-insert trigger : Before Event Trigger « Trigger « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Trigger
3. Before Event Trigger

SQL>
SQL> CREATE TABLE incremented_values
  2  (value_inserted    NUMBER,
  3   value_incremented NUMBER);

Table created.

SQL>
SQL> CREATE OR REPLACE TRIGGER increment_by_one
  2  BEFORE INSERT ON incremented_values
  3  FOR EACH ROW
  4  BEGIN
  5    :new.value_incremented := :new.value_incremented + 1;
  6  END;
  7  /

Trigger created.

SQL>
SQL> CREATE OR REPLACE TRIGGER increment_by_two
  2  BEFORE INSERT ON incremented_values
  3  FOR EACH ROW
  4  BEGIN
  5    IF :new.value_incremented > 1 THEN
  6      :new.value_incremented := :new.value_incremented + 2;
  7    END IF;
  8  END;
  9  /

Trigger created.

SQL>
SQL> INSERT INTO incremented_values VALUES(1,1);

1 row created.

SQL>
SQL> SELECT * FROM incremented_values;

VALUE_INSERTED VALUE_INCREMENTED
-------------- -----------------
             1                 2

SQL>
SQL>
SQL> DROP TABLE incremented_values;

Table dropped.

SQL>