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T-SQL Query | [ The Complex Time Puzzle ]
- We have a table called “Flag”
- We need two columns in the output i.e. Time1 and Time2
- There is a sequence of Time in Tim column with ID = 1 and ID = 2. Conside ID = 1 as the start time and ID = 2 as the End Time
- In the Time1 column we have to pick value from Tim column where ID = 1 and the in the Time2 column we have to pick value from Tim column where ID = 2 (Immediate next Id)
- For each Id = 1, if the next row is not ID = 2 then show value ‘0:00:00’
- Same if for Id = 2 if the previous value is not id = 1 then show value ‘0:00:00’
- Please check out the sample input and expected output for details.
- Your solution should be should use “SELECT” statement or “CTE”
- Your solution should be generic in nature.
- Add your solution(s) in the comments section or send you solution(s) to firstname.lastname@example.org
Use the below script to generate the source table and fill them up with the sample data.
-- CREATE TABLE Flag ( ID INT ,Tim VARCHAR(8) ) GO INSERT INTO Flag(ID,Tim) VALUES (1,'9:05:00'), (2,'9:10:00'), (1,'10:00:00'), (2,'10:15:00'), (1,'11:00:00'), (1,'11:30:00'), (2,'11:45:00'), (2,'11:50:00') --
UPDATE – 23-Apr-2015 – Solution 1
-- ;WITH CTE AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) - ID rnk , * FROM Flag ) ,CTE1 AS ( SELECT MIN(Tim) Time1, MAX(Tim) Time2 FROM CTE GROUP BY rnk ) SELECT CASE WHEN Time1 = Time2 AND ID = 2 THEN '0:00:00' ELSE Time1 END Time1 ,CASE WHEN Time1 = Time2 AND ID = 1 THEN '0:00:00' ELSE Time2 END Time2 FROM CTE1 a INNER JOIN Flag b ON a.Time1 = b.Tim --
UPDATE – 28-Apr-2015 – Solution 2
--Posted By Isha Mattoo ;With cte AS ( Select *,ISnull(lag(ID) OVER (ORDER BY (select null)),0) As Prev_ID ,ISnull(Lead(ID) OVER (ORDER BY (select null)),0) As Next_ID from Flag ) ,cte2 as( select * , case when id = 1 and (next_id = 2 or Prev_id =2 or next_id = 0) then Tim when id = 2 and Prev_ID = 2 then '00:00:00' end as Tim1 , CASE WHEN id = 2 and (Prev_id = 1 or next_id = 1 or next_id = 0) then Tim when id = 1 and Next_ID = 1 then '00:00:00' end as Tim2 from cte ) ,CTE21 AS ( SELECT Tim1 , ROW_NUMBER() OVER (ORDER BY (SELECT 1)) rnk from cte2 WHERE Tim1 IS NOT NULL ) ,CTE22 AS ( SELECT Tim2 , ROW_NUMBER() OVER (ORDER BY (SELECT 1)) rnk from cte2 WHERE Tim2 IS NOT NULL ) SELECT Tim1,Tim2 FROM CTE22 c INNER JOIN CTE21 c1 on c.rnk = c1.rnk --
Add a comment if you have any other solution in mind. We all need to learn.