Solution

calculate_largest_expensors.sql

@@ -0,0 +1,39 @@
+USE memory.default;
+-- We're preparing total expenses for employees
+with expense_totals as (
+    select
+        employee_id,
+        sum(unit_price * quantity) as total_expensed_amount
+    from
+        expense
+    group by
+        employee_id
+    having 
+        sum(unit_price * quantity) > 1000
+),
+
+-- lookup for employee name
+employee_lookup as (
+    select
+        e.employee_id,
+        e.first_name || ' ' || e.last_name as employee_name,
+        e.manager_id,
+        m.first_name || ' ' || m.last_name as manager_name
+    from
+        employee e
+    left join employee m on e.manager_id = m.employee_id
+)
+
+-- Final query combining both
+select
+    et.employee_id,
+    el.employee_name,
+    el.manager_id,
+    el.manager_name,
+    et.total_expensed_amount
+from
+    expense_totals et
+join
+    employee_lookup el on et.employee_id = el.employee_id
+order by
+    et.total_expensed_amount desc

create_employees.sql

@@ -0,0 +1,19 @@
+USE memory.default;
+
+CREATE TABLE employee (
+    employee_id TINYINT,
+    first_name VARCHAR,
+    last_name VARCHAR,
+    job_title VARCHAR,
+    manager_id TINYINT
+);
+
+INSERT INTO employee VALUES (1, 'Ian', 'James', 'CEO', 4);
+INSERT INTO employee VALUES (2, 'Umberto', 'Torrielli', 'CSO', 1);
+INSERT INTO employee VALUES (3, 'Alex', 'Jacobson', 'MD EMEA', 2);
+INSERT INTO employee VALUES (4, 'Darren', 'Poynton', 'CFO', 2);
+INSERT INTO employee VALUES (5, 'Tim', 'Beard', 'MD APAC', 2);
+INSERT INTO employee VALUES (6, 'Gemma', 'Dodd', 'COS', 1);
+INSERT INTO employee VALUES (7, 'Lisa', 'Platten', 'CHR', 6);
+INSERT INTO employee VALUES (8, 'Stefano', 'Camisaca', 'GM Activation', 2);
+INSERT INTO employee VALUES (9, 'Andrea', 'Ghibaudi', 'MD NAM', 2);

create_expenses.sql

@@ -0,0 +1,31 @@
+USE memory.default;
+
+--Let's first create table and inserts for the data, disregarding Items desciption as it is not needed moving forward
+
+CREATE TABLE if NOT EXISTS expense_employee_full_name (
+  employee_name VARCHAR(100),
+  unit_price DECIMAL(8, 2),
+  quantity TINYINT
+);
+
+INSERT INTO expense_employee_full_name (employee_name, unit_price, quantity) VALUES
+('Alex Jacobson', 6.50, 14),
+('Alex Jacobson', 11.00, 20),
+('Alex Jacobson', 22.00, 18),
+('Alex Jacobson', 13.00, 75),
+('Andrea Ghibaudi', 300.00, 1),
+('Darren Poynton', 40.00, 9),
+('Umberto Torrielli', 17.50, 4);
+
+
+CREATE TABLE if NOT EXISTS expense (
+  employee_id TINYINT,
+  unit_price DECIMAL(8, 2),
+  quantity TINYINT
+);
+
+-- Now we'll fill out expense table getting employee id's from employee table based on their fist and last name (assume here that employee first and last name are one word)
+INSERT INTO expense
+SELECT emp.employee_id, ex.unit_price, ex.quantity
+FROM expense_employee_full_name ex
+JOIN  employee emp on emp.first_name = split(ex.employee_name, ' ')[1] and emp.last_name = split(ex.employee_name, ' ')[2]

create_invoices.sql

@@ -0,0 +1,38 @@
+USE memory.default;
+
+create table if not exists supplier (
+    supplier_id tinyint,
+    name varchar
+);
+
+
+create table if not exists invoice (
+    supplier_id tinyint,
+    invoice_ammount decimal(8, 2),
+    due_date date
+);
+
+create table if not exists invoice_raw (
+    company_name varchar,
+    invoice_amount decimal(8, 2),
+    due_date varchar
+);
+
+--Load the raw data
+insert into invoice_raw (company_name, invoice_amount, due_date) values
+('party animals', 6000, '3 months from now'),
+('catering plus', 2000, '2 months from now'),
+('catering plus', 1500, '3 months from now'),
+('dave''s discos', 500, '1 month from now'),
+('entertainment tonight', 6000, '3 months from now'),
+('ice ice baby', 4000, '6 months from now');
+
+--Translate company names to id's alphabetically and getting due date (based on the current date)
+INSERT INTO invoice
+SELECT
+    dense_rank() over (order by company_name asc) as num,
+    invoice_amount,
+    date_add('month', cast(split(due_date, ' ')[1] as integer), last_day_of_month(current_date)) as due_date
+FROM
+    invoice_raw
+

find_manager_cycles.sql

@@ -0,0 +1,19 @@
+USE memory.default;
+-- Let's check paths employee -> their manager -> their manager -> ...
+-- We stop when we encounter employee_id already present in the path
+-- If the last employee_id is the same as the one we started with, it means we have a cycle
+
+WITH RECURSIVE cycle(employee_id, path) AS (
+    SELECT employee_id, ARRAY[manager_id]
+    FROM employee
+
+    UNION ALL
+
+    SELECT c.employee_id, path || ARRAY[e.manager_id]
+    FROM cycle c
+    JOIN employee e ON c.path[cardinality(c.path)] = e.employee_id
+    WHERE NOT contains(c.path, e.manager_id)
+)
+SELECT *
+FROM cycle
+WHERE contains(path, employee_id);

generate_supplier_payment_plans.sql

@@ -0,0 +1,51 @@
+USE memory.default;
+--first, we create a list of all payments - amount and date
+--ten we aggregate by date of payment
+--add the end window functions to get cumulative sum and amount left to be paid
+WITH RECURSIVE installments(supplier_id, num_of_installments_left, payment, due_date) AS (
+    SELECT
+        i.supplier_id,
+        date_diff('month', last_day_of_month(current_date), i.due_date) AS num_of_installments_left,
+        i.invoice_ammount / (date_diff('month', last_day_of_month(current_date), i.due_date) + 1),
+        last_day_of_month(current_date) AS due_date
+    FROM invoice i
+
+    UNION ALL
+
+    SELECT
+        supplier_id,
+        num_of_installments_left - 1,
+        payment,
+        due_date + interval '1' month
+    FROM installments
+    WHERE num_of_installments_left > 0
+)
+SELECT
+    supplier_id,
+    supplier_name,
+    payment,
+    SUM(payment) OVER (PARTITION BY supplier_name) -
+    SUM(payment) OVER (
+        PARTITION BY supplier_name
+        ORDER BY payment_date
+        ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
+    ) AS balance_outstanding,
+    payment_date
+FROM (
+SELECT
+    i.supplier_id,
+    s.supplier_name,
+    i.due_date as payment_date,
+    SUM(i.payment) AS payment
+FROM installments i
+JOIN (
+    SELECT
+        RANK() OVER (ORDER BY company_name ASC) AS supplier_id,
+        company_name AS supplier_name
+    FROM (
+        SELECT DISTINCT company_name FROM invoice_raw
+    )
+) s ON i.supplier_id = s.supplier_id
+GROUP BY i.supplier_id, s.supplier_name, i.due_date
+) payments
+ORDER BY supplier_id, payment_date;