Question

I have a table :

TABLE A

   ID (PK)(Identity seed)
   Key (nvarchar) (Unique Hashed Keys)

Data:

   ID          Key
   ----------- --------------------------------------------------
   1           ++0a4rZicJ68kProEpK/ig                            
   2           ++0Coy1S7szg3NjLi2kMLQ                            
   3           ++0eeYiZuRPxsiVVsBcfdg                            
   4           +F07I6n6kLvC/I98So8Y+w                            
   5           +f/RK7VMWIIo5IfUcMujmg  

TABLE B : (Without PK)

   Content (nvarchar)
   SortKey (nvarchar) 

Data :

   Content          SortKey 
   ----------- --------------------------------------------------
   TEST1           ++0a4rZicJ68kProEpK/ig                            
   TEST2           ++0Coy1S7szg3NjLi2kMLQ                            
   TEST3           ++0eeYiZuRPxsiVVsBcfdg                            
   TEST4           +F/ZdeGRjbC4sP6ulQnOvg                            
   TEST5           +f0+6vJcwY++Xdx5lch1kQ 
   TEST6           +f/RK7VMWIIo5IfUcMujmg <-- Expected Result starts here
   TEST7           +F07I6n6kLvC/I98So8Y+w
   TEST8           +f0990bHYJUOXkyME+0kmg   

Query :

SELECT top 3 * 
FROM 
    TABLEB 
WHERE 
    SortKey > (SELECT top 1 Key 
               FROM TABLEA 
               ORDER BY ID DESC)
ORDER BY 
    SortKey 

The above query gives me the desired result which is greater than the SortKey (++1l32JdpYoHzXTCIp4jSA):

TEST6           +f/RK7VMWIIo5IfUcMujmg 
TEST7           +F07I6n6kLvC/I98So8Y+w
TEST8           +f0990bHYJUOXkyME+0kmg 

Once I get this result I need to get the final (last record) key again to do an insert on another table, so I need to get the key of TEST8 in this scenario i.e. : f/RK7VMWIIo5IfUcMujmg.

How do I do this in a single query and not have to write 2 separate queries?

Answer 1

You could use ROW_NUMBER()

WITH CTE AS 
(
SELECT
      ROW_NUMBER() OVER (ORDER BY CONTENT DESC) rn,
      Content,
      SortKey
FROM   tableb 
WHERE  sortkey < (SELECT TOP 1 [key] 
                  FROM   tablea 
                  ORDER  BY id DESC) 
 )
SELECT 
     Content,
     SortKey 
FROM CTE 
WHERE RN = 1

DEMO