Question

I’m attempting to run a report which will give me daily “plot” sales over the past 3 months and I’m having a hard time getting SUM() to add up correctly. A single Transaction_ID may span across several Plot records. With the query below, if there are 2 plots with the same Transaction_ID, it is adding them together, which is not what I want. I need it to only use a Transaction row once within the SUM().

SELECT 
    DATE_FORMAT(Transactions.CreateDate,'%m-%d') AS MonthAndDay, 
    DATE_FORMAT(Transactions.CreateDate,'%M, %D') AS Day, 
    SUM(Transactions.AmountTotal) AS DailySales 
FROM 
    Transactions, 
    Plots 
WHERE 
    Transactions.Transaction_ID = Plots.Transaction_ID AND 
    Transactions.CreateDate <= CURDATE() AND 
    Transactions.CreateDate >= DATE_SUB(CURDATE(),INTERVAL 3 MONTH) 
GROUP BY 
    MonthAndDay 
ORDER BY 
    MonthAndDay ASC 

The table structures look like so:

+-----------------------------------+----------------------------------------------------------------------------------------------------+------+-----+---------------------+----------------+
| Field                             | Type                                                                                               | Null | Key | Default             | Extra          |
+-----------------------------------+----------------------------------------------------------------------------------------------------+------+-----+---------------------+----------------+
| Transaction_ID                    | int(11)                                                                                            | NO   | PRI | NULL                | auto_increment | 
| CreateDate                        | datetime                                                                                           | NO   |     | 0000-00-00 00:00:00 |                | 
| AmountTotal                       | decimal(10,2)                                                                                      | NO   |     | 0.00                |                | 
+-----------------------------------+----------------------------------------------------------------------------------------------------+------+-----+---------------------+----------------+

+------------------------+-------------+------+-----+---------------------+----------------+
| Field                  | Type        | Null | Key | Default             | Extra          |
+------------------------+-------------+------+-----+---------------------+----------------+
| Plot_ID                | int(11)     | NO   | PRI | NULL                | auto_increment | 
| Transaction_ID         | int(11)     | YES  | MUL | NULL                |                | 
| Plot                   | varchar(10) | NO   |     | 0                   |                | 
+------------------------+-------------+------+-----+---------------------+----------------+

Answer 1

The following solution works, albeit with a subquery:

SELECT
   DATE_FORMAT(Transactions.CreateDate,'%m-%d') AS MonthAndDay,
   DATE_FORMAT(Transactions.CreateDate,'%M, %D') AS Day,
   SUM(Transactions.AmountTotal) AS DailySales
FROM
   Transactions
WHERE
   Transactions.Transaction_ID IN (SELECT DISTINCT Transaction_ID FROM Plots) AND
   Transactions.CreateDate <= CURDATE() AND
   Transactions.CreateDate >= DATE_SUB(CURDATE(),INTERVAL 3 MONTH)
GROUP BY
   MonthAndDay
ORDER BY
   MonthAndDay ASC;