Oracle convert table to interval day(3) to second - oracle

Question

I have the following table definition, with data that creates fine but I like to convert it to a more generic format but I'm having issues. Can someone point me in the right direction
CREATE TABLE partition_retention
(
seq_num NUMBER GENERATED BY DEFAULT AS IDENTITY (START WITH 1) NOT NULL,
TABLE_NAME VARCHAR2(30),
DAYS NUMBER(6),
CONSTRAINT
partition_retention_pk primary key (table_name));
/
INSERT into partition_retention(TABLE_NAME, DAYS)
WITH data as (
select 'T1', 0
from dual union all
select 'T3', 15
from dual union all
select 'T4', 10
from dual union all
select 'T5', 5
from dual)
SELECT * from data;
/
-- having problem creating
CREATE TABLE PARTITION_RETENTION AS (
TABLE_NAME AS VARCHAR2(30)
RETENTION DAY AS INTERVAL DAY(3) TO SECOND(0)
);

Answer 1

The three AS keywords are invalid (create table .. as select .. is valid, but you aren't doing that); you are missing a comma; and you have an unquoted column name with a space.
Correcting those things, this works:
CREATE TABLE PARTITION_RETENTION (
TABLE_NAME VARCHAR2(30),
RETENTION_DAY INTERVAL DAY(3) TO SECOND(0)
);
Your inserts will then have to insert interval values, not simple numbers, obviously.
db<>fiddle
how can I add a CONSTRAINT on the table to ensure the day>0 and the time is always 0
You can add separate constraints to check both things:
CREATE TABLE PARTITION_RETENTION (
TABLE_NAME VARCHAR2(30),
RETENTION_DAY INTERVAL DAY(3) TO SECOND(0),
CONSTRAINT CHK_NON_ZERO_DAYS CHECK (
RETENTION_DAY > INTERVAL '0' DAY
),
CONSTRAINT CHK_WHOLE_DAYS CHECK (
EXTRACT(HOUR FROM RETENTION_DAY) = 0
AND EXTRACT(MINUTE FROM RETENTION_DAY) = 0
AND EXTRACT(SECOND FROM RETENTION_DAY) = 0
)
);
to give slightly different errors (via the constraint names) - db<>fiddle - or combine them into one.
I'm not sure this is really any clearer or easier than having a number column constrained to integers between 1 and 999.