Question

Here is my select statement,

SELECT TOP 1
  EmpId, RemainingAdvance 
FROM SalaryDetails
WHERE EmpId IN (SELECT Emp_Id
                FROM Employee
                WHERE Desig_Id='27')
ORDER BY CreatedDate DESC

When i executed SELECT Emp_Id FROM Employee WHERE Desig_Id='27' the results were

Emp_Id
16
17

But when i execute my first statement it gives me result for only 16 but no output 17…
I have records for both EmpId’s in SalaryDetails Table…..

EDIT:

Removing TOP 1 from my query i got this,

SELECT EmpId, RemainingAdvance FROM SalaryDetails 
where EmpId in (select Emp_Id from Employee where Desig_Id='27')
               ORDER BY CreatedDate DESC 

gave me

I want results for EmpId 16,17 ORDER BY CreatedDate DESC… Because my now my Desig_Id='27' and i will change it with a variable @CategoryId … So there may be ‘n’ number of employees based on @CategoryId

EmpId  RemainingAdvance
16                354.00
17                 0.00

Answer 1

SELECT SD.EmpId, SD.RemainingAdvance 
FROM 
SalaryDetails SD INNER JOIN 
   (SELECT SD2.EmpID, MAX(SD2.CreatedDate) AS MAXDate 
   FROM SalaryDetails SD2 GROUP BY SD2.EmpID) AS SD2
ON SD.EmpID = SD2.EmpID
INNER JOIN Employee E
ON SD.EmpID = E.EmpID
WHERE E.Desig_Id = '27' AND SD.CreatedDate = SD2.MaxDate

Note: The query is written without trying it out.
I suppose, this is what you are looking for.

---

This variant also works (in at least one DBMS – namely IBM Informix Dynamic Server 11.50):

SELECT SD.EmpId, SD.RemainingAdvance 
  FROM SalaryDetails SD
       INNER JOIN 
       (SELECT SD2.EmpID, MAX(SD2.CreatedDate) AS MAXDate 
          FROM SalaryDetails SD2 GROUP BY SD2.EmpID) AS SD2
       ON SD.EmpID = SD2.EmpID AND SD.CreatedDate = SD2.MaxDate
       INNER JOIN Employee E
       ON SD.EmpID = E.EmpID
 WHERE E.Desig_Id = '27'

The compound join in the first ON clause might improve the performance of the query – but it is quite possible that the optimizer would hoist the ‘AND SD.CreatedDate = SD2.MaxDate’ condition anyway, meaning you wouldn’t spot any difference even if you examined the two query plans. I’m not quite sure of the best way to indent the table expressions after the main FROM clause.

Edited by Jonathan Leffler – as requested by Shahkalpesh.