Calculating age from birthday with oracle plsql trigger and insert the age in table

Question

i have a table

dates
(dob date,
age number(4)
);

I will insert a date of birth and a trigger will calculate the age and insert that age in

Answer 1

If you want AGE to be available from the database there are two options:

1. Define a view which contains the age computation, or
2. Define a virtual column which does the same

To define such a view:

CREATE OR REPLACE VIEW DATES_VIEW
  AS SELECT DOB,
            FLOOR(MONTHS_BETWEEN(SYSDATE, DOB) / 12) AS AGE
        FROM DATES

The problem with this is that you have to remember that you SELECT from DATES_VIEW, but need to update DATES, which is mentally messy. IMO adding a virtual column to the table is cleaner:

CREATE TABLE DATES
  (DOB      DATE,
   AGE      GENERATED ALWAYS AS (FLOOR(MONTHS_BETWEEN(SYSDATE, DOB) / 12)) VIRTUAL);

Note that virtual columns cannot be updated.

Either method helps to ensure that AGE will always be consistent.

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