将sql表行与同一表的所有其他行联接

Question

I'm beginner in SQL Server querying. I have assigned to a task where I need to self join a table.

Above is table structure. And I need result as below. I have tried using self join , sub query etc. I couldn't get result.

ReqStatusId ReqStatus ChildId  ChildReqStatus
1           Open      2        On Hold 
1           Open      3        Closed  
2           On Hold   1        Open       
2           On Hold   3        Closed  
3           Closed    1        Open       
3           Closed    2        On Hold  

Result should come as: Each row in a table should joined with all other rows

Answer 1

use CROSS JOIN , Which gives you the Cartesian product between two tables

Select * 
From YourTable A
CROSS JOIN YourTable B
Where A.ReqStatusId <> B.ReqStatusId 

Answer 2

What you are trying to get is achieved through a cross join . If you select the table twice you would get the desired result.

select a.reqstatusid, a.reqstatus, b.reqstatusid as childreqstatusid,
b.reqstatus as childreqstatus
from table a, table b
where a.reqstatusid <> b.reqstatusid

Answer 3

You should do a JOIN on ReqStatusId <> ReqStatusId :

WITH Tbl(ReqStatusId, ReqStatus) AS(
    SELECT 1, 'Open' UNION ALL
    SELECT 2, 'On Hold' UNION ALL
    SELECT 3, 'Closed'
)
SELECT
    t1.*,
    ChildId = t2.ReqStatusId,
    ChildReqStatus = t2.ReqStatus
FROM Tbl t1
INNER JOIN Tbl t2
    ON t2.ReqStatusId <> t1.ReqStatusId

Answer 4

select a.reqstatusid, a.reqstatus, b.reqstatusid,
b.reqstatus
from table a
inner join table b on A.ReqStatusId = B.ReqStatusId 
Where A.ReqStatusId <> B.ReqStatusId