Sum is not done if joined table is empty with MySQL - mysql

Question

I have the following tables structure and trying to make a report from these:
___BillableDatas
|--------|------------|---------|--------------|------------|
| BIL_Id | BIL_Date |BIL_Rate | BIL_Quantity | BIL_Status |
|--------|------------|---------|--------------|------------|
| 1 | 2018-03-01 | 105 | 1 | charged |
| 2 | 2018-03-01 | 15 | 2 | notcharged |
| 3 | 2018-03-01 | 5 | 1 | notcharged |
|--------|------------|---------|--------------|------------|
___SalesTaxes
|--------|--------------|------------|
| STX_Id | STX_TaxeName | STX_Amount |
|--------|--------------|------------|
| 8 | Tax 1 | 5.000 |
| 9 | Tax 2 | 15.000 |
|--------|--------------|------------|
STX_Amount is a percentage.
___ApplicableTaxes
|-----------|-----------|
| ATX_BILId | ATX_STXId |
|-----------|-----------|
| 1 | 8 |
| 1 | 9 |
|-----------|-----------|
ATX_BILId is the item ID link with ___BillableDatas.
ATX_STXId is the tax ID link with ___SalesTaxes.
I need to get to sum of the items per day
- without tax
- with tax
So mething like this:
|------------------|---------------|------------|
| BIL_RateNonTaxed | BIL_RateTaxed | BIL_Status |
|------------------|---------------|------------|
| 105.00 | 126.00 | charged | <- Taxes #8, #9 applicable
| 35.00 | 35.00 | notcharged | <- No taxes here
|------------------|---------------|------------|
Explications on the totals:
105 = 105*1 -- (total of the charged item multiply by the quantity)
35 = (15*2)+5 -- (total of the notcharged items multiply by the quantity)
126.00 = 105+(105*(5+15)/100)
35.00 = as no taxe, put the non taxed value.
My last try was this one:
SELECT BIL_Status
, SUM(BIL_Rate*BIL_Quantity) BIL_RateNonTaxed
, IFNULL(SUM((BIL_Rate*BIL_Quantity)+(BIL_Rate*BIL_Quantity*total_sales_tax/100)), SUM(BIL_Rate*BIL_Quantity)) BIL_RateTaxed
FROM
( SELECT b.*
, SUM(t.STX_Amount) total_sales_tax
FROM ___BillableDatas b
LEFT JOIN ___ApplicableTaxes bt
ON bt.ATX_BILId = b.BIL_Id
LEFT JOIN ___SalesTaxes t
ON t.STX_Id = bt.ATX_STXId
GROUP
BY ATX_BILId
) x
GROUP
BY BIL_Status
This query works just when each item has a linked taxe (case of my item #1). When item has no linked taxes (item #2 and #3), the sum is not made.
Please see this SQLFiddle to help you if needed:
http://sqlfiddle.com/#!9/433a3f/2
The only one error with the link is I should have 35 and not 30.
Thanks.

Answer 1

The subquery was grouping by the wrong thing. You are grouping by ATX_BILId, but I think you really wanted to get all the unique billable data bill_ids. At least the following query returns what you expected. The only difference is changing "GROUP BY ATX_BILId" to "GROUP BY BIL_Id"
SELECT BIL_Status
, SUM(BIL_Rate*BIL_Quantity) BIL_RateNonTaxed
, IFNULL(SUM((BIL_Rate*BIL_Quantity)+(BIL_Rate*BIL_Quantity*total_sales_tax/100)), SUM(BIL_Rate*BIL_Quantity)) BIL_RateTaxed
FROM
( SELECT b.*
, SUM(t.STX_Amount) total_sales_tax
FROM ___BillableDatas b
LEFT JOIN ___ApplicableTaxes bt
ON bt.ATX_BILId = b.BIL_Id
LEFT JOIN ___SalesTaxes t
ON t.STX_Id = bt.ATX_STXId
GROUP
BY BIL_Id
) x
GROUP
BY BIL_Status
Link to SQL Fiddle
In general, when you are troubleshooting this type of query, the first thing to do is examine the returned rows without the group bys. It becomes easier to see the problem when you run the following query.
SELECT BIL_Status,
BIL_Rate,
BIL_Quantity,
total_sales_tax
FROM
( SELECT b.*
, SUM(t.STX_Amount) total_sales_tax
FROM ___BillableDatas b
LEFT JOIN ___ApplicableTaxes bt
ON bt.ATX_BILId = b.BIL_Id
LEFT JOIN ___SalesTaxes t
ON t.STX_Id = bt.ATX_STXId
GROUP
BY ATX_BILId
) x