SQL - Select distinct column without excluding rows - mysql

Question

I'm running a query that aggregates sales information by either category or subcategory within some date range. I was asked to add budget information to it for a report that displays the information fetched by this query.
SELECT
DATE_FORMAT(B.TxnDate, "%Y-%m") AS FormattedTxnDate,
SUM(B.Quantity) AS QuantitySum,
SUM(B.Quantity * B.Amount) AS Revenue,
SUM(CASE WHEN B.AverageCost = 0 THEN (B.Quantity * C.PurchaseCost) ELSE (B.Quantity *
B.AverageCost) END) AS COGS,
A.CustomerRefFullName,
SUM(D.Budget_2018) AS Budget,
D.Brand, D.Category, D.Subcategory, D.ProductManager, C.VendorRefFullName
FROM
qb_invoice_info A, qb_invoice_line_info B, qb_item_info C, qb_item_group D
WHERE
A.TxnID = B.TxnID
AND
B.Item_ListID = C.ListID
AND
C.Parent_ListID = D.ListID
AND
(C.Type = "Inventory" OR C.Type = "InventoryAssembly")
AND
B.TxnDate BETWEEN ? AND ?
GROUP
BY D.Category, YEAR(B.TxnDate), QUARTER(B.TxnDate)
ORDER
BY D.Category ASC, YEAR(B.TxnDate) ASC, QUARTER(B.TxnDate) ASC
Every subcategory has its own budget amount. The problem is that some subcategories share all of the same information except for their unique IDs. A few records might look like this within the qb_item_group table.
qb_item_group
id | Category | Subcategory | Budget
------------------------------------
1A | Lights | DMX | 4000
1B | Lights | DMX | 4000
1C | Lights | DMX | 4000
2A | Lights | Flash | 5000
3A | Lights | Bulbs | 1000
In this case, the total budget for lights would be 10,000 because we ignore two of the DMX budgets. I tried SUM(DISTINCT D.Budget_2018 AS Budget earlier today but it failed as I expected because it's only adding unique budget values. How can I adapt the query I have above so that I can retrieve all sales records by either category or subcategory but still get a total budget that is the sum of all unique subcategories under the parent category?

Answer 1

SELECT
DATE_FORMAT(B.TxnDate, "%Y-%m") AS FormattedTxnDate,
SUM(B.Quantity) AS QuantitySum,
SUM(B.Quantity * B.Amount) AS Revenue,
SUM(
CASE
WHEN B.AverageCost = 0 THEN (B.Quantity * C.PurchaseCost)
ELSE (B.Quantity * B.AverageCost)
END
) AS COGS,
A.CustomerRefFullName,
COALESCE(category_budgets.budget, 0) AS budget,
D.Brand,
D.Category,
D.Subcategory,
D.ProductManager,
C.VendorRefFullName
FROM
qb_invoice_info A,
qb_invoice_line_info B,
qb_item_info C,
qb_item_group D
LEFT JOIN
(
SELECT
a.category,
SUM(a.budget) as budget
FROM
(
SELECT DISTINCT
category
budget
FROM
budgets
) a
) category_budgets
ON
category_budgets.category = D.category
WHERE
A.TxnID = B.TxnID
AND
B.Item_ListID = C.ListID
AND
C.Parent_ListID = D.ListID
AND
(C.Type = "Inventory" OR C.Type = "InventoryAssembly")
AND
B.TxnDate BETWEEN ? AND ?
GROUP BY
D.Category, YEAR(B.TxnDate), QUARTER(B.TxnDate)
ORDER BY
D.Category ASC, YEAR(B.TxnDate) ASC, QUARTER(B.TxnDate) ASC
;
You can left join with the sum of distinct categories and budgets. This will give you all of your output rows desired but will also give you $0 budgets for categories that don't have entries in the budgets table. Good luck!