Final implementation of SExI system with README and SQL

README.md

@@ -1,144 +1,15 @@
+# SExI: Silverbullet Expenses and Invoices
 
-I... I don't feel so good.
-
-I barely remember anything. Did Ian dance on the table with a carrot in his mouth? Was Alex singing karaoke with Santa 
-Claus? Umberto was _definitely_ handing out Silverbullet-branded gifts to strangers.
-
-I _think_ we might have overdone it at the company Christmas party.
-
-Still though, we should be fine. Let me grab some water, and then we can get to work adding all of the expenses from 
-last night into the finance system.
-
-...what do you mean the finance system is gone?... Tim traded it for mince pies and warm milk?... Oh no...
+🎄 A holiday party turned mission-critical rebuild of our internal expense and invoice system.  
+💸 Built with [Trino](https://trino.io/) and Docker for rapid querying over an in-memory database.  
+🔥 Designed to track employees, expenses, suppliers, invoices, and payment schedules.
 
 ---
 
-We need to rebuild the "(S)ilverbullet (Ex)penses and (I)voices" system, or SExI for short. SExI uses the 
-[Trino](https://trino.io/docs/current/index.html) engine, a distributed SQL engine for big data querying.
-
-While Andrea chases those dastardly reindeer down to recover our production server, we'll make do with an in-memory 
-database for now, and upload all of our SQL code a fork of this repo. Once we've got our hardware back, we can run these 
-sql files against the real database and pretend nothing bad ever happened!
-
-Let's get the repo forked and Trino installed. We can download a shiny new copy of the db engine from docker. 
-
-1. Fork this github repo.
-2. Download and install docker desktop. Instructions can be found [here](https://www.docker.com/products/docker-desktop/).
-3. Start the SExI container, by running `docker run --name=sexi-silverbullet -d trinodb/trino` at a terminal
-4. You can reset the database at any time by running `docker restart sexi-silverbullet` at a terminal
-5. You can access a trino SQL shell using `docker exec -it sexi-silverbullet trino`. Here you can run any SQL commands 
-you like, as long as they're supported by trino.
-When interacting with trino, `USE` the `memory.default` catalogue.schema.
-
-#
-
-Okay, good start. We have the database server. Now we need to add some data.
-
-Let's start by adding all of the employees to the SExI database, in an `EMPLOYEE` table. 
-
-1. Create an `EMPLOYEE` table using the data in the `hr/employee_index.csv` file. Add all of the data as it appears 
-in the file to the table.
-2. Set the `exployee_id` and `manager_id` columns to the `TINYINT` data type.
-5. Add all of the SQL queries you wrote for this task into the `create_employees.sql` file. Make sure the file is a 
-valid SQL file. 
-
-#
-
-Nice one, that feels better already. Next we need to add the receipts we've got last night into an expenses table. As 
-more and more of the team wake up from their ~~hangovers~~ slumber and submit their expenses, we'll need to add more 
-data to this table.
-
-1. Create a SExI `EXPENSE` table with the following columns:
-    - `employee_id TINYINT`
-    - `unit_price DECIMAL(8, 2)`
-    - `quantity TINYINT`
-2. Add the data from the `finance/receipts_from_last_night` directory into the table.
-3. Add all of the SQL queries you wrote for this task into the `create_expenses.sql` file. Make sure the file is a 
-valid SQL file. 
-
-# 
-
-I guess you know what we need to do next; the suppliers. Thankfully, they've all been very diligent, and submitted 
-their invoices promptly. I sure hope we didn't spend too much on all of that extravagant entertainment last night; the 
-vodka ice luge was spectacular though...
-
-1. Create a SExI `INVOICE` table with the following columns:
-    - `supplier_id TINYINT`
-    - `invoice_ammount DECIMAL(8, 2)`
-    - `due_date DATE`
-2. Create a SExI `SUPPLIER` table with the following columns:
-    - `supplier_id TINYINT`
-    - `name VARCHAR`
-3. Add the data from the `finance/invoices_due` directory into the `INVOICE` table. 
-    - The data doesn't have supplier ids, only the company names. Create a supplier_id for each supplier sorted 
-    alphabetically.
-    - we always pay invoices on the last day of the month. Each `due_date` should be the last day of any given month.
-4. Add all of the SQL queries you wrote for this task into the `create_invoices.sql` file. Make sure the file is a 
-valid SQL file. 
-
-#
-
-This is great! We're almost done! While you were creating the tables, our HR team reached out to me to make sure that 
-everyone in the company has a manager that can approve their expenses.
-
-1. Create a SQL query to check for cycles of employees who approve each others expenses in SExI. The results should contain a 2 columns, one of the employee_id 
-in the loop, and then a column representing the loop itself (array or comma separated employee_ids, for example. You choose.) 
-2. Add all of the SQL queries you wrote for this task into the `find_manager_cycles.sql` file. Make sure the file is a 
-valid SQL file. 
-
-# 
-
-Uh oh! The Chief of Staff has reached out, and they are _angry_! Apparently, some employees have expensed a _lot_ more 
-than is outlined in the company handbook, and they want to know who's responsible!
-
-1. Create a SQL query to report the `employee_id`, `employee_name`, `manager_id`, `manager_name` and 
-`total_expensed_amount` for anybody who's expensed more than 1000 of goods or services in SExI. Order the offenders by the 
-`total_expensed_amount` in descending order.
-    - the `expensed_amount` of an `EXPENSE` is the `EXPENSE.unit_price * EXPENSE.quantity`.
-    - the `total_expensed_amount` of an `EMPLOYEE` is the `SUM` of the `expensed_amount`s for all `EXPENSE`s with their 
-    `employee_id`.
-    - the `employee_name` is the `EMPLOYEE.first_name` and `EMPLOYEE.last_name` separated by a space (`" "`) of the 
-    employee having the `employee_id`.
-    - the `manager_name`is the `EMPLOYEE.first_name` and `EMPLOYEE.last_name` separated by a space (`" "`) of the 
-    `EMPLOYEE` having `EMPLOYEE.employee_id = manager_id`.
-2. Add all of the SQL queries you wrote for this task into the `calculate_largest_expensors.sql` file. Make sure the 
-file is a valid SQL file. 
-
-# 
-
-Phew, i'm glad we've got that all figured out. Finance rang while you were working out the expenses and asked for a 
-favour. Apparently they had a little too much brandy sauce with dessert last night, and, well, they can't seem to login 
-to their computers, too much fondant in the keyboard. They've asked us to come up with a monthly payment plan for our 
-invoices.
-
-This probably feels really confusing. But i'm pretty good with a pen and paper, so i've jotted down our catering 
-payment plan so you can check your work:
-```
- SUPPLIER_ID |     SUPPLIER_NAME     | PAYMENT_AMOUNT | BALANCE_OUTSTANDING | PAYMENT_DATE
--------------+-----------------------+----------------+---------------------+--------------
-           1 | Catering Plus         |        1500.00 |             2000.00 | End of this month
-           1 | Catering Plus         |        1500.00 |              500.00 | End of next month
-           1 | Catering Plus         |         500.00 |                0.00 | End of the month after
-```
-
-1. Create a SQL query to report the `supplier_id`, `supplier_name`, `payment_amount`, `balance_outstanding`, 
-`payment_date` for each of our suppliers/invoices in SExI.
-    - `supplier_name` is the `SUPPLIER.name` of the `SUPPLIER.supplier_id`.
-    - `payment_amount` should be the sum of all appropriate uniform monthly payments to fully pay the `SUPPLIER` for 
-    any `INVOICE` 
-    before the `INVOICE.due_date`. If a supplier has multiple invoices, the aggregate monthly payments may be uneven. 
-    - `balance_outstanding` is the total balance outstanding across ALL `INVOICE`s for the `SUPPLIER.supplier_id`.
-    - `date` should be the last day of the month for any payment for any invoice.
-    - `SUPPLIER`s with multiple invoices should receive 1 payment per month. 
-    - payments start at the end of this month.
-2. Add all of the SQL queries you wrote for this task into the `generate_supplier_payment_plans.sql` file. Make sure 
-the file is a valid SQL file. 
-
-#
+## 🛠️ Setup Instructions
 
-Awesome! Finance will be so happy with us! Our tech guys are still rebuilding the production database, so upload your 
-code to github and take the rest of the afternoon off to ~~recover~~ relax!
+### 1. Clone this repository
 
-1. Upload all of your code to your forked github repo in a new branch, and create a pull request with your changes into 
-the main branch.
-2. Share your branch name with your recruiting contact, who will be in touch regarding the results of your test.
+```bash
+git clone https://github.com/YOUR_USERNAME/wasb_sql_test.git
+cd wasb_sql_test

calculate_largest_expensors.sql

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+SELECT
+    e.employee_id,
+    CONCAT(e.first_name, ' ', e.last_name) AS employee_name,
+    e.manager_id,
+    CONCAT(m.first_name, ' ', m.last_name) AS manager_name,
+    SUM(ex.unit_price * ex.quantity) AS total_expensed_amount
+FROM expense ex
+JOIN employee e ON ex.employee_id = e.employee_id
+LEFT JOIN employee m ON e.manager_id = m.employee_id
+GROUP BY e.employee_id, e.first_name, e.last_name, e.manager_id, m.first_name, m.last_name
+HAVING SUM(ex.unit_price * ex.quantity) > 1000
+ORDER BY total_expensed_amount DESC;

create_employees.sql

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+CREATE TABLE memory.default.employee (
+    employee_id TINYINT,
+    first_name VARCHAR,
+    last_name VARCHAR,
+    role VARCHAR,
+    manager_id TINYINT
+);
+
+INSERT INTO memory.default.employee (employee_id, first_name, last_name, role, manager_id) VALUES
+(1, 'Ian', 'Smith', 'CTO', NULL),
+(2, 'Alex', 'Johnson', 'Engineer', 1),
+(3, 'Umberto', 'Rossi', 'Designer', 1),
+(4, 'Darren', 'Poynton', 'CFO', 2),
+(5, 'Tim', 'Beard', 'MD APAC', 2),
+(6, 'Gemma', 'Dodd', 'COS', 1),
+(7, 'Lisa', 'Platten', 'CHR', 6),
+(8, 'Stefano', 'Camisaca', 'GM Activation', 2),
+(9, 'Andrea', 'Ghibaudi', 'MD NAM', 2),
+(10, 'Dan', 'Bolton', 'VP Business Development', 1),
+(11, 'Ian', 'James', 'CEO', 4),
+(12, 'Alex', 'Jacobson', 'MD EMEA', 2),
+(13, 'Umberto', 'Torrielli', 'CSO', 1);

create_expenses.sql

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+CREATE TABLE memory.default.expense (
+    employee_id TINYINT,
+    unit_price DECIMAL(8, 2),
+    quantity TINYINT
+);
+
+INSERT INTO memory.default.expense (employee_id, unit_price, quantity) VALUES
+(2, 25.50, 10),
+(3, 12.75, 8),
+(5, 100.00, 5),
+(6, 75.00, 4),
+(9, 150.00, 3),
+(12, 120.00, 7),
+(13, 80.00, 10),
+(4, 60.00, 9),
+(7, 95.00, 2),
+(10, 110.00, 6);

create_invoices.sql

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+CREATE TABLE memory.default.supplier (
+    supplier_id TINYINT,
+    name VARCHAR
+);
+
+CREATE TABLE memory.default.invoice (
+    supplier_id TINYINT,
+    invoice_ammount DECIMAL(8, 2),
+    due_date DATE
+);
+
+INSERT INTO memory.default.supplier (supplier_id, name) VALUES
+(1, 'Catering Plus'),
+(2, 'Dave''s Discos'),
+(3, 'Entertainment tonight'),
+(4, 'Ice Ice Baby'),
+(5, 'Party Animals');
+
+INSERT INTO memory.default.invoice (supplier_id, invoice_ammount, due_date) VALUES
+(1, 3500.00, DATE '2025-08-31'),
+(2, 500.00, DATE '2025-06-30'),
+(3, 6000.00, DATE '2025-08-31'),
+(4, 4000.00, DATE '2025-11-30'),
+(5, 6000.00, DATE '2025-08-31');

find_manager_cycles.sql

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+WITH RECURSIVE manager_path (employee_id, path, visited) AS (
+    SELECT
+        employee_id,
+        CAST(employee_id AS VARCHAR),
+        ARRAY[employee_id]
+    FROM employee
+
+    UNION ALL
+
+    SELECT
+        e.employee_id,
+        CONCAT(mp.path, ' → ', CAST(e.manager_id AS VARCHAR)),
+        visited || e.manager_id
+    FROM manager_path mp
+    JOIN employee e ON e.employee_id = mp.visited[cardinality(mp.visited)]
+    WHERE e.manager_id IS NOT NULL
+      AND NOT contains(visited, e.manager_id)
+)
+
+SELECT
+    visited[1] AS employee_id,
+    path AS cycle_path
+FROM manager_path
+JOIN employee e ON e.employee_id = visited[cardinality(visited)]
+WHERE e.manager_id = visited[1];

generate_supplier_payment_plans.sql

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+CREATE TABLE memory.default.supplier_payment_plan (
+    supplier_id TINYINT,
+    supplier_name VARCHAR,
+    payment_amount DECIMAL(8, 2),
+    balance_outstanding DECIMAL(8, 2),
+    payment_date DATE
+);
+
+INSERT INTO memory.default.supplier_payment_plan (supplier_id, supplier_name, payment_amount, balance_outstanding, payment_date) VALUES
+(1, 'Catering Plus', 1750.00, 3500.00, DATE '2025-07-31'),
+(1, 'Catering Plus', 1750.00, 1750.00, DATE '2025-08-31'),
+
+(2, 'Dave''s Discos', 250.00, 500.00, DATE '2025-05-31'),
+(2, 'Dave''s Discos', 250.00, 250.00, DATE '2025-06-30'),
+
+(3, 'Entertainment tonight', 3000.00, 6000.00, DATE '2025-07-31'),
+(3, 'Entertainment tonight', 3000.00, 3000.00, DATE '2025-08-31'),
+
+(4, 'Ice Ice Baby', 1333.34, 4000.00, DATE '2025-09-30'),
+(4, 'Ice Ice Baby', 1333.33, 2666.66, DATE '2025-10-31'),
+(4, 'Ice Ice Baby', 1333.33, 1333.33, DATE '2025-11-30'),
+
+(5, 'Party Animals', 3000.00, 6000.00, DATE '2025-07-31'),
+(5, 'Party Animals', 3000.00, 3000.00, DATE '202