Teradata date subtract issue in PERIOD column - teradata

Question

I have a teradata table ABC . I have a column in the table which is of PERIOD data type ( Name of the column is ef_dtm) . I need to update the starting bound of the period column(subtract it by 1 day) whenever starting bound of the period column is '12/31/9999'.
I am using the below query . But it is saying
INVALID Interval Literal.
Can you suggest me an update query?
Nonsequenced validtime
update ABC
set ef_dtm = PERIOD(CAST(end(ef_dtm) as Date) -INTERVAL '-1' DAY , end(ef_dtm))
where begin(ef_dtm) = '12/31/9999'

Answer 1

The error is because of part INTERVAL '-1' DAY
It should be INTERVAL -'1' DAY i.e. minus - outside the '1'
Your query has 2 more problems.
No need to cast period begin to DATE as INTERVAL arithmetic works on TIMESTAMP
DATE literals are wrong. It should be YYYY-MM-DD; Moreover it should be TIMESTAMP corresponding to period column datatype.
Correct query is as below.
nonsequenced validtime
UPDATE ABC
SET ef_dtm = PERIOD(begin(ef_dtm) + INTERVAL -'1' DAY, end(ef_dtm))
WHERE begin(ef_dtm) = TIMESTAMP '1999-12-31 00:00:00.000000';
OR
nonsequenced validtime
UPDATE ABC
SET ef_dtm = PERIOD(begin(ef_dtm) - INTERVAL '1' DAY, end(ef_dtm))
WHERE begin(ef_dtm) = TIMESTAMP '1999-12-31 00:00:00.000000';
DEMO
Create Table:
CREATE TABLE ABC ( ef_dtm period(timestamp(6)) AS validtime ) NO PRIMARY INDEX;
Insert Data:
INSERT INTO abc(period (TIMESTAMP '1999-12-31 00:00:00.000000', TIMESTAMP '1999-12-31 23:59:00.000000'));
After select
ef_dtm
------------------------------------------------------------
('1999-12-31 00:00:00.000000', '1999-12-31 23:59:00.000000')
Update Data:
nonsequenced validtime
UPDATE ABC
SET ef_dtm = PERIOD(begin(ef_dtm) + INTERVAL -'1' DAY, end(ef_dtm))
WHERE begin(ef_dtm) = TIMESTAMP '1999-12-31 00:00:00.000000';
After SELECT
ef_dtm
------------------------------------------------------------
('1999-12-30 00:00:00.000000', '1999-12-31 23:59:00.000000')