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  1. Prepare
  2. SQL
  3. Advanced Join
  4. SQL Project Planning
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SQL Project Planning

  • timcottenio
     + 73 comments

    A simple MySQL implementation without variables and only requiring DATEDIFF():

    SET sql_mode = '';
SELECT Start_Date, 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 DATEDIFF(End_Date, Start_Date), Start_Date

    Edits: Updated with the sql_mode='' based on @jakab922's comment. HackerRank changed the default sql_mode behavior to only_full_group_by at some point after I posted this.

    Also, a full solution without the need to change modes was posted by @dougal_michael below, which uses the MIN() function instead.