周，月，年至周初的日期

Question

Example:

• Month Number : 03
• Week Number: 10
• Year : 2018

I want this to convert to 3/05/2018 but am unsure how to do this in Tableau/Oracle SQL. What would be the logic to convert these 3 separate numbers into the beginning of a week? The week would start on Monday.

Thanks

Answer 1

The following query should give you the desired result -

SELECT
    TO_CHAR(START_DATE,'MM/DD/YYYY') AS START_DATE
FROM
(
    SELECT 
        (TRUNC(TO_DATE('2018','YYYY'),'DAY') + 1) + ((LEVEL - 1) * 7) AS START_DATE,
        (TRUNC(TO_DATE('2018','YYYY'),'DAY') + 1) + ((LEVEL - 1) * 7) + 6 AS END_DATE, LEVEL AS WEEK
    FROM 
        DUAL
    CONNECT BY LEVEL <= (((TO_DATE('2018','YYYY') + INTERVAL '1' YEAR) + INTERVAL '-1' DAY) - (TO_DATE('2018','YYYY')))/7
)
WHERE
    WEEK = 10
;

The year 2018 and week number 10 are hardcoded here to get the desired result in this case.

Result:-

START_DATE

03/05/2018

Answer 2

I think Month Number is not necessary, you can try below code,

SELECT NEXT_DAY(TO_DATE((&week_no*7)||' &yyyy', 'DDD YYYY')-7, 2) date_
  FROM dual;

week_no = 10
yyyy = 2018

DATE_   
---------
05-MAR-18