How to write sql query to get the below result

Question

I have a table with below data.

And the expected result will be below data.

Here step1 completion date is arrival date of step2 and the step2 completion date is arrival date of step3.

How to write SQL query to get this result.

Answer 1

This Script gives your expected Result

;With Cte(
id,StepName,ArrivalDate,duedate
)
AS
(
SELECT 1,'Step1','25/12/2017','1/1/2018' UNION ALL
SELECT 2,'Step2','26/12/2017','1/1/2018' UNION ALL
SELECT 3,'Step3','27/12/2017','1/1/2018' 
)
SELECT
     id
     ,StepName
     ,ArrivalDate
     ,duedate
     ,ISNULL(LEAD(ArrivalDate,1)OVER(ORDER BY ArrivalDate),'') AS CompletionDate
FROM CTE

Result

id  StepName    ArrivalDate duedate    CompletionDate
-----------------------------------------------------
1   Step1       25/12/2017  1/1/2018    26/12/2017
2   Step2       26/12/2017  1/1/2018    27/12/2017
3   Step3       27/12/2017  1/1/2018    

Answer 2

This should serve your purpose, completion date as startdate from next id

SELECT x.id
    ,x.stepname
    ,x.arrival_date
    ,x.due_date
    ,isnull(y.arrival_date, '') Completion_date
FROM x
LEFT JOIN (
    SELECT id
        ,step1
        ,step2
        ,arrival_date
    FROM x
    ) y ON x.id = y.id + 1

Answer 3

Give a row number based on ascending order of id column.(If id column has any gaps). Then use a LEFT JOIN / RIGHT JOIN with rn = rn + 1 .

Query

;with cte as(
    select [rn] = row_number() over(
        order by [id]
    ), *
    from [your_table_name]
)
select t1.[stepName], t1.[ArrivalDate], t1.[dueDate], 
coalesce(t2.[dueDate], '') as [completiondate]
from cte t1
left join cte t2
on t1.[rn] + 1 = t2.[rn];

Answer 4

some_logical_grouping_of_data shoud define group of data which can be used for.

Select ID, stepname, arrival_date, duedate, 
LEAD ( arrival_date) OVER ( partition by "some_logical_grouping_of_data" order by ID) as completion_date
from table;

Answer 5

It's a bad idea to join data based on String suffixes. I assume that step1 always has ID 1 , step13 always has ID 13 and so on. Then you can do something like

SELECT t1.ID, t1.Stepname, t1.arrival_date, t2.arrival_date as completion_date 
    FROM tablename t1 
    LEFT JOIN tablename t2 on t1.ID + 1 = t2.ID;