Oracle 18c

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SELECT DATE '2021-01-01' + LEVEL - 1 AS value
FROM   DUAL
CONNECT BY DATE '2021-01-01' + LEVEL - 1 <= DATE '2021-01-03';


VALUE


01-JAN-21

02-JAN-21

03-JAN-21


WITH date_ranges ( start_date, end_date ) AS (
  SELECT DATE '2021-01-01', DATE '2021-01-03' FROM DUAL
UNION ALL
  SELECT start_date + 1, end_date FROM date_ranges WHERE start_date + 1 <= end_date
)
SELECT start_date AS value
FROM   date_ranges;


VALUE


01-JAN-21

02-JAN-21

03-JAN-21


WITH date_range ( start_date ) AS (
  SELECT DATE '2021-01-01' FROM DUAL
)
SELECT start_date AS col1,
       start_date + 1 AS col2,
       start_date + 2 AS col3
FROM   date_range;


COL1
COL2
COL3


01-JAN-21
02-JAN-21
03-JAN-21