How to create Date column from month and year given in oracle sql?

Question

I want to create a date column which would take 'year' and 'month' and give me a date starts from 1st

E_name  s_date      year  month
  a    01-08-2012   2012   MAR
  a    23-06-2012   2010   DEC 
  a    19-03-2020   2020   DEC
  a    14-02-2020   2020   MAR
  b    27-12-2018   2018   DEC

REQUIRED OUTPUT

E_name  s_date      year  month  Date
  a    01-08-2012   2012   MAR   01-03-2012
  a    23-06-2012   2010   DEC   01-12-2010
  a    19-03-2020   2020   DEC   01-12-2020
  a    14-02-2020   2020   MAR   01-03-2020
  b    27-12-2018   2018   DEC   01-12-2018

  

Answer 1

Concatenate the year and month columns and then use TO_DATE :

SELECT t.*,
       TO_DATE(month || year, 'MONYYYY', 'NLS_DATE_LANGUAGE=American') AS "Date"
FROM   table_name t

Which, for your sample data:

CREATE TABLE table_name (E_name, s_date, year, month) AS
SELECT 'a', DATE '2012-08-01', 2012, 'MAR' FROM DUAL UNION ALL
SELECT 'a', DATE '2012-06-23', 2010, 'DEC' FROM DUAL UNION ALL
SELECT 'a', DATE '2020-03-19', 2020, 'DEC' FROM DUAL UNION ALL
SELECT 'a', DATE '2020-02-14', 2020, 'MAR' FROM DUAL UNION ALL
SELECT 'b', DATE '2018-12-27', 2018, 'DEC' FROM DUAL;

Outputs:

E_NAME	S_DATE	YEAR	MONTH	Date
a	01-08-2012	2012	MAR	01-03-2012
a	23-06-2012	2010	DEC	01-12-2010
a	19-03-2020	2020	DEC	01-12-2020
a	14-02-2020	2020	MAR	01-03-2020
b	27-12-2018	2018	DEC	01-12-2018

db<>fiddle here