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Without Group By Clause

Hi All,

I'm trying to write this query to group results by ev_id but can't seem to once I start selecting from the order table (TAmount). The query is as follows:

SELECT E.ev_id,E.ev_name, (SELECT count(*) as evOrdTot from tbl_book_orders where or_ev_id = E.ev_id) AS totOrd
,( SELECT SUM(oi_qty * oi_price) AS TotAmount from tbl_book_orderItems WHERE oi_or_id = BO.or_id) AS TAmount
FROM tbl_booking_events E
LEFT JOIN tbl_book_orders BO ON E.ev_id = BO.or_ev_id
LEFT JOIN tbl_book_orderItems OI ON BO.or_id = OI.oi_or_id

Thanks

rajvja

Are you getting any error

ASKER CERTIFIED SOLUTION

Rajkumar Gs

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Rajkumar Gs

In my query,
COUNT(BO.order_id) AS evOrdTot ,
replace by
COUNT(*) AS evOrdTot ,

SELECT  E.ev_id ,
        E.ev_name ,
        COUNT(BO.*) AS evOrdTot ,
        SUM(OI.oi_qty * OI.oi_price) AS TotAmount
FROM    tbl_booking_events E
        LEFT JOIN tbl_book_orders BO ON E.ev_id = BO.or_ev_id
        LEFT JOIN tbl_book_orderItems OI ON BO.or_id = OI.oi_or_id
GROUP BY E.ev_id ,
        E.ev_name

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What is your issue ?

Raj

rajvja

Hi,

I think the author asked to execute the query without GROUP BY

If not getting an error, are the results unexpected?

This might be due to LEFT JOIN. If there is no match, it returns NULL. NULL multiplies with any other value is also NULL.

Rajkumar Gs

Sorry. I forgot about question title.

Without GROUP BY same ev_id may shown repeatly in the result with the same count and sum

Try INNER JOIN

SELECT  E.ev_id ,
        E.ev_name ,
        ( SELECT    COUNT(*) AS evOrdTot
          FROM      tbl_book_orders
          WHERE     or_ev_id = E.ev_id
        ) AS totOrd ,
        ( SELECT    SUM(oi_qty * oi_price) AS TotAmount
          FROM      tbl_book_orderItems
          WHERE     oi_or_id = BO.or_id
        ) AS TAmount
FROM    tbl_booking_events E
        INNER JOIN tbl_book_orders BO ON E.ev_id = BO.or_ev_id
        INNER JOIN tbl_book_orderItems OI ON BO.or_id = OI.oi_or_id

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Rajkumar Gs

I suggest GROUP BY

@pigmentarts, Please explain so that we can get you
Raj

pigmentarts

ASKER

Well I am not getting any errors the query runs fine just that I am getting duplicate results which I don't want. I am trying to give users a summary of items ordered for an event but only want to show the event and a total of all orders placed for that event. I'm sure there may be a better way of writing it.

Guy Hengel [angelIII / a3]

this article should be read: https://www.experts-exchange.com/A_3203.html

pigmentarts

ASKER

Currently the results look as such with the event 'Test2' being repeated when it should be grouped with the one below. I need the Query to be fast as there will be alot of data to get through.

Event ev_id
Test2        1            1250
Test2        1            NULL
Test 2            NULL
Dinner        3            NULL

Rajkumar Gs

>> ..I am getting duplicate results ..
That I mentioned already-
Without GROUP BY same ev_id may shown repeatly in the result with the same count and sum

Try this query - http:#34996698
Why you are trying to avoid GROUP BY ?

Raj

Rajkumar Gs

Also try your query itself by replacing LEFT JOIN with INNER JOIN - http:#34996734

NULL is because of LEFT JOIN.
Better option is using GROUP BY

pigmentarts

ASKER

The only reason I was trying to avoid the Group By Clause is because they can be in-efficient when running against a database that has thousands of results which this will have. If this is the best way then I'll go ahead and use the Group By clause, I just thought there may have been a better way for writing this script.

pigmentarts

ASKER

The query you provided 'RajkumarGS' seems to do the trick