Dear All,
I have a query as below SELECT DISTINCT (productID),totalAmountAfter,transactionDate FROM tbltransaction WHERE transactionDate BETWEEN '2010-01-01' AND '2010-12-31' ORDER BY productID,transactionDate DESC .
My problem now I want is that for each product only pick one line that is the last line since I have ordered by the date. But even using distinct I still get a more than one data for each productID. Any solution for this?

because the combination containing productid, totalAmountAfter, transactionDate is what the distinct applies to, not just the productID,

Dear John,
Any solution to my problem? Thank you.

Along those lines:

SELECT productID,totalAmountAfter,transactionDate FROM tbltransaction
WHERE transactionDate BETWEEN '2010-01-01' AND '2010-12-31' 
and (productID, transactionDate) in
(SELECT productID, max(transactionDate) from tbltransaction group by productID)
ORDER BY productID,transactionDate DESC

Dear Smant,
Your query works but it took me 5 minutes plus wow. How to solve the timing issue?

Set an index on transactionDate.
Study the output of EXPLAIN <thequery> for optimisation hints.
How often do you have to run the query, anyway? Maybe you are better of by caching the result instead of optimizing the run-time behaviour of the query.

Dear Smant,
I have added the index is still the same. Here is my explain but key,key_len and ref are all null here.
ID SelectType table type possibleKeys rows extra
"1 PRIMARY tbltransaction ALL NewIndex1 24391 Using where; Using filesort"
"2 DEPENDENT SUBQUERY tbltransaction ALL 24391 Using temporary; Using filesort"

Looks like you don't have an index on productID. Isn't that your primary key? Show the output of CREATE TABLE tbltransaction

Dear Smant,
You are right I am missing that.But the index which I have build do you recommend or shall I remove those?

CREATE TABLE `tbltransaction` (                                                                        
                  `transactionID` INT(10) NOT NULL,                                                                    
                  `transactionDetailsID` INT(10) NOT NULL,                                                             
                  `stockID` INT(10) NOT NULL,                                                                          
                  `productID` INT(5) NOT NULL,                                                                         
                  `outletFromID` INT(2) NOT NULL,                                                                      
                  `outletToID` INT(2) NOT NULL,                                                                        
                  `totalAmountBefore` DOUBLE(10,2) NOT NULL,                                                           
                  `totalAmountAfter` DOUBLE(10,2) NOT NULL,                                                            
                  `totalQuantityBefore` INT(10) NOT NULL,                                                              
                  `totalQuantityAfter` INT(10) NOT NULL,                                                               
                  `averageCostBefore` DOUBLE(10,2) NOT NULL,                                                           
                  `averageCostAfter` DOUBLE(10,2) NOT NULL,                                                            
                  `quantity` INT(10) NOT NULL,                                                                         
                  `costPrice` DOUBLE(10,2) NOT NULL,                                                                   
                  `transactionPrice` DOUBLE(10,2) NOT NULL,                                                            
                  `transactionEmployeeID` INT(2) NOT NULL,                                                             
                  `transactionDate` DATE NOT NULL,                                                                     
                  `transactionTime` TIME NOT NULL,                                                                     
                  `transactionType` ENUM('ti','to','tif','tof','i','r','e','f','p','s','g') NOT NULL,                  
                  PRIMARY KEY (`transactionID`,`transactionDetailsID`,`outletFromID`,`outletToID`,`transactionType`),  
                  KEY `NewIndex1` (`transactionDate`)                                                                  
                ) ENGINE=INNODB DEFAULT CHARSET=latin1

Set an index on productID. Test with the EXPLAIN <query> statement if it is used by the query optimiser.
Other indexes which are not used by query optimisation are irrelevant - it does not harm to keep them.

Dear Smant,
After adding the index on productID it became worse where my whole sql client crash.

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	PRIMARY	tbltransaction	ALL	NewIndex1	\N	\N	\N	24391	Using where; Using filesort
2	DEPENDENT SUBQUERY	tbltransaction	index	\N	NewIndex2	4	\N	13
CREATE TABLE `tbltransaction` (                                                                        
                  `transactionID` INT(10) NOT NULL,                                                                    
                  `transactionDetailsID` INT(10) NOT NULL,                                                             
                  `stockID` INT(10) NOT NULL,                                                                          
                  `productID` INT(5) NOT NULL,                                                                         
                  `outletFromID` INT(2) NOT NULL,                                                                      
                  `outletToID` INT(2) NOT NULL,                                                                        
                  `totalAmountBefore` DOUBLE(10,2) NOT NULL,                                                           
                  `totalAmountAfter` DOUBLE(10,2) NOT NULL,                                                            
                  `totalQuantityBefore` INT(10) NOT NULL,                                                              
                  `totalQuantityAfter` INT(10) NOT NULL,                                                               
                  `averageCostBefore` DOUBLE(10,2) NOT NULL,                                                           
                  `averageCostAfter` DOUBLE(10,2) NOT NULL,                                                            
                  `quantity` INT(10) NOT NULL,                                                                         
                  `costPrice` DOUBLE(10,2) NOT NULL,                                                                   
                  `transactionPrice` DOUBLE(10,2) NOT NULL,                                                            
                  `transactionEmployeeID` INT(2) NOT NULL,                                                             
                  `transactionDate` DATE NOT NULL,                                                                     
                  `transactionTime` TIME NOT NULL,                                                                     
                  `transactionType` ENUM('ti','to','tif','tof','i','r','e','f','p','s','g') NOT NULL,                  
                  PRIMARY KEY (`transactionID`,`transactionDetailsID`,`outletFromID`,`outletToID`,`transactionType`),  
                  KEY `NewIndex1` (`transactionDate`),                                                                 
                  KEY `NewIndex2` (`productID`)                                                                        
                ) ENGINE=INNODB DEFAULT CHARSET=latin1
SELECT productID,totalAmountAfter,transactionDate 
FROM(
SELECT * from tbltransaction 
WHERE transactionDate BETWEEN '2010-01-01' AND '2010-12-31'
) A
having A.transactionDate =max(A.transactionDate )

Should work

Dear Voidyman,
I run the query but it gave me empty results? Why ya?

do you have data for this date range? try running the inner query alone(within the from)

Dear Voidyman,
Yes I have confirm by running via the inner query there is data in that range?

I dnt know newbie14.. I have run a similar query and it seems to work fine for me..

Dear Voidyman,
Is very surprising to me why it works for you and not on my end. Anything else possible is my mistake?

Submit a complete test case - CREATE TABLE statements, INSERT statements and the query which does not work - and we will be able to track down the mistake.