SQL Project Planning.sql

/* Write a query to output the start and end dates of projects listed by the number of days it took to complete the project in ascending order. 
If there is more than one project that have the same number of completion days, then order by the start date of the project. */

-- 
-- Author: Pavith Bambaravanage
-- URL: https://github.com/Pavith19
-- 

SELECT Start_Date, MIN(End_Date)
FROM (SELECT Start_Date FROM Projects WHERE Start_Date NOT IN 
    (SELECT End_Date FROM Projects)) a,
    (SELECT End_Date FROM Projects WHERE End_Date 
    NOT IN (SELECT Start_Date FROM Projects)) b 
WHERE Start_Date < End_Date
GROUP BY Start_Date  ORDER BY min(end_date)- start_date asc, Start_Date;