Calculate tax amount between 3 different tables 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 | 2018-03-02 | 105 | 1 | cancelled |
| 3 | 2018-03-01 | 15 | 2 | notcharged |
| 4 | 2018-03-01 | 21 | 1 | notcharged |
| 5 | 2018-03-02 | 15 | 2 | notcharged |
| 6 | 2018-03-02 | 21 | 1 | notcharged |
|--------|------------|---------|--------------|------------|
___SalesTaxes
|--------|--------------|------------|
| STX_Id | STX_TaxeName | STX_Amount |
|--------|--------------|------------|
| 8 | Tax 1 | 5.000 |
| 9 | Tax 2 | 5.000 |
| 10 | Tax 3 | 19.975 |
|--------|--------------|------------|
STX_Amount is a percentage.
___ApplicableTaxes
|-----------|-----------|
| ATX_BILId | ATX_STXId |
|-----------|-----------|
| 1 | 8 |
| 1 | 9 |
| 1 | 10 |
| 2 | 8 |
| 2 | 9 |
| 2 | 10 |
| 3 | 9 |
| 3 | 10 |
| 4 | 9 |
| 5 | 9 |
| 5 | 10 |
| 6 | 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 | 136.47 | charged | <- Taxes #8, #9 and #10 applicable
| 102.00 | 118.035 | notcharged | <- Taxes #9 and #10 applicable
|------------------|---------------|------------|
Explications on the totals:
105 = 105*1 -- (total of the charged item multiply by the quantity)
102 = (15*2)*2+(21*2) -- (total of the notcharged items multiply by the quantity)
136.47 = 105+(105*(5+5+19.975)/100)
119.085 = 102+(((15*2)*2)*(5+19.975)/100+(21*2)*5/100)
My last try was this one:
SELECT
BIL_Date,
(BIL_Rate*BIL_Quantity) AS BIL_RateNonTaxed,
(((BIL_Rate*BIL_Quantity)*SUM(STX_Amount)/100)+BIL_Rate*BIL_Quantity) AS BIL_RateTaxed,
BIL_Status
FROM ___BillableDatas
LEFT JOIN ___SalesTaxes
ON FIND_IN_SET(STX_Id, BIL_ApplicableTaxes) > 0
LEFT JOIN ___ApplicableTaxes
ON ___BillableDatas.BIL_Id = ___ApplicableTaxes.ATX_BILId
WHERE BIL_BookingId=1
GROUP BY BIL_Id AND BIL_Status
ORDER BY BIL_Date
ASC
Please see this SQLFiddle to help you if needed:
http://sqlfiddle.com/#!9/425854f
Thanks.

Answer 1

I cannot bear to work with your naming policy, so I made my own...
DROP TABLE IF EXISTS bills;
CREATE TABLE bills
(bill_id SERIAL PRIMARY KEY
,bill_date DATE NOT NULL
,bill_rate INT NOT NULL
,bill_quantity INT NOT NULL
,bill_status ENUM('charged','cancelled','notcharged')
);
INSERT INTO bills VALUES
(1,'2018-03-01',105,1,'charged'),
(2,'2018-03-02',105,1,'cancelled'),
(3,'2018-03-01',15,2,'notcharged'),
(4,'2018-03-01',21,1,'notcharged'),
(5,'2018-03-02',15,2,'notcharged'),
(6,'2018-03-02',21,1,'notcharged');
DROP TABLE IF EXISTS sales_taxes;
CREATE TABLE sales_taxes
(sales_tax_id SERIAL PRIMARY KEY
,sales_tax_name VARCHAR(12) NOT NULL
,sales_tax_amount DECIMAL(5,3) NOT NULL
);
INSERT INTO sales_taxes VALUES
( 8,'Tax 1', 5.000),
( 9,'Tax 2', 5.000),
(10,'Tax 3',19.975);
DROP TABLE IF EXISTS applicable_taxes;
CREATE TABLE applicable_taxes
(bill_id INT NOT NULL
,sales_tax_id INT NOT NULL
,PRIMARY KEY(bill_id,sales_tax_id)
);
INSERT INTO applicable_taxes VALUES
(1, 8),
(1, 9),
(1,10),
(2, 8),
(2, 9),
(2,10),
(3, 9),
(3,10),
(4, 9),
(5, 9),
(5,10),
(6, 9);
SELECT bill_status
, SUM(bill_rate*bill_quantity) nontaxed
, SUM((bill_rate*bill_quantity)+(bill_rate*bill_quantity*total_sales_tax/100)) taxed
FROM
( SELECT b.*
, SUM(t.sales_tax_amount) total_sales_tax
FROM bills b
JOIN applicable_taxes bt
ON bt.bill_id = b.bill_id
JOIN sales_taxes t
ON t.sales_tax_id = bt.sales_tax_id
GROUP
BY bill_id
) x
GROUP
BY bill_status;
+-------------+---------+-------------+
| bill_status | untaxed | total |
+-------------+---------+-------------+
| charged | 105 | 136.4737500 |
| cancelled | 105 | 136.4737500 |
| notcharged | 102 | 119.0850000 |
+-------------+---------+-------------+
My answer is very slightly different from yours, so one of us has made a mistake somewhere. Either way, this should get you pretty close.

Answer 2

SELECT a.BIL_Date, BIL_RateNonTaxed, BIL_RateNonTaxed+BIL_RateTaxed AS BIL_RateTaxed FROM (
SELECT BIL_Date,
SUM(BIL_Rate*BIL_Quantity) AS BIL_RateNonTaxed
FROM ___BillableDatas
WHERE BIL_Status != 'cancelled'
GROUP BY BIL_Date
) a INNER JOIN (
SELECT BIL_Date,
(((BIL_Rate*BIL_Quantity)*SUM(STX_Amount)/100)) AS BIL_RateTaxed
FROM ___BillableDatas
LEFT JOIN ___ApplicableTaxes
ON ___BillableDatas.BIL_Id = ___ApplicableTaxes.ATX_BILId
LEFT JOIN ___SalesTaxes
ON STX_Id = ATX_STXId
WHERE BIL_Status != 'cancelled'
GROUP BY BIL_Date
) b
ON a.BIL_Date = b.BIL_Date
ORDER BY a.BIL_Date;
Explanation:
Your BIL_RateNonTaxed calculation is not using the ___SalesTaxes table, so it must not appear on the query otherwise it would interfere the SUM function.
Howerver, your BIL_RateTaxed does use the ___SalesTaxes table. In that case, I solved by creating 2 subqueries and joining the results.
I know there are better answers, but I'm not familiar with MySQL syntax.