solution for wasb_sql_test

calculate_largest_expensors.sql

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+-- Query to report employees who expensed more than 1000
+WITH EmployeeExpenses AS (
+	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
+    INNER 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
+)
+SELECT
+    employee_id,
+    employee_name,
+    manager_id,
+    manager_name,
+    total_expensed_amount
+FROM
+    EmployeeExpenses
+WHERE
+	total_expensed_amount > 1000
+ORDER BY
+    total_expensed_amount DESC;

create_employees.sql

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+USE MEMORY.DEFAULT;
+
+-- Create EMPLOYEE table
+CREATE TABLE IF NOT EXISTS EMPLOYEE (
+    employee_id TINYINT,
+    first_name VARCHAR,
+    last_name VARCHAR,
+    job_title VARCHAR,
+    manager_id TINYINT
+);
+
+-- Insert data into EMPLOYEE table
+INSERT INTO EMPLOYEE (
+    employee_id, first_name, last_name, job_title, manager_id
+) VALUES
+    (1, 'Ian', 'James', 'CEO', 4),
+    (2, 'Umberto', 'Torrielli', 'CSO', 1),
+    (3, 'Alex', 'Jacobson', 'MD EMEA', 2),
+    (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);

create_expenses.sql

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+USE MEMORY.DEFAULT;
+
+-- Create EXPENSE table using a CTE
+CREATE TABLE IF NOT EXISTS EXPENSE AS
+WITH EXPENSE_WITH_FULL_NAME (employee_full_name, unit_price, quantity) AS (
+    VALUES
+        ('Alex Jacobson', 6.50, 14),
+        ('Alex Jacobson', 11.00, 20),
+        ('Alex Jacobson', 22.00, 18),
+        ('Alex Jacobson', 13.00, 75),
+        ('Andrea Ghibaudi', 40.00, 9),
+        ('Andrea Ghibaudi', 17.50, 4)
+),
+EXPENSE_WITH_ID (employee_id, unit_price, quantity) AS (
+    SELECT
+        EMPLOYEE.employee_id,
+        CAST(TMP_EXPENSE.unit_price AS DECIMAL(8, 2)) AS unit_price,
+        CAST(TMP_EXPENSE.quantity AS TINYINT) AS quantity
+    FROM
+        EMPLOYEE
+    INNER JOIN
+        EXPENSE_WITH_FULL_NAME TMP_EXPENSE
+    ON
+        EMPLOYEE.first_name = SPLIT_PART(TMP_EXPENSE.employee_full_name, ' ', 1)
+        AND EMPLOYEE.last_name = SPLIT_PART(TMP_EXPENSE.employee_full_name, ' ', 2)
+)
+SELECT
+    CAST(employee_id AS INT) AS employee_id,
+    CAST(unit_price AS DECIMAL(8, 2)) AS unit_price,
+    CAST(quantity AS TINYINT) AS quantity
+FROM EXPENSE_WITH_ID;

create_invoices.sql

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+USE MEMORY.DEFAULT;
+
+-- Create SUPPLIER table
+CREATE TABLE IF NOT EXISTS SUPPLIER AS (
+    WITH SUPPLIER_NAMES AS (
+        SELECT DISTINCT company_name
+        FROM (
+            VALUES
+                ('Party Animals', 6000, 3),
+                ('Catering Plus', 2000, 2),
+                ('Catering Plus', 1500, 3),
+                ('Dave''s Discos', 500, 1),
+                ('Entertainment tonight', 6000, 3),
+                ('Ice Ice Baby', 4000, 6)
+        ) AS invoices_due(company_name, invoice_amount, due_date)
+    ),
+    SUPPLIER_ASSIGNING_IDS_BY_ORDER AS (
+        SELECT
+            ROW_NUMBER() OVER (ORDER BY company_name) AS supplier_id,
+            company_name
+        FROM SUPPLIER_NAMES
+    )
+    SELECT
+        CAST(supplier_id AS TINYINT) AS supplier_id,
+        CAST(company_name AS VARCHAR) AS name
+    FROM SUPPLIER_ASSIGNING_IDS_BY_ORDER
+);
+
+-- Create INVOICE table
+CREATE TABLE IF NOT EXISTS INVOICE AS (
+    WITH INVOICES_DUE (company_name, invoice_amount, invoice_date) AS (
+        VALUES
+            ('Party Animals', 6000, 3),
+            ('Catering Plus', 2000, 2),
+            ('Catering Plus', 1500, 3),
+            ('Dave''s Discos', 500, 1),
+            ('Entertainment tonight', 6000, 3),
+            ('Ice Ice Baby', 4000, 6)
+    ),
+    INVOICE_WITH_SUPPLIER_IDS AS (
+        SELECT
+            S.supplier_id,
+            I.invoice_amount,
+            I.invoice_date
+        FROM
+            INVOICES_DUE I
+        INNER JOIN
+            SUPPLIER S
+        ON
+            I.company_name = S.name
+    )
+    SELECT
+        CAST(supplier_id AS TINYINT) AS supplier_id,
+        CAST(invoice_amount AS DECIMAL(8, 2)) AS invoice_amount,
+        LAST_DAY_OF_MONTH(DATE_ADD('MONTH', invoice_date, CURRENT_DATE)) AS due_date
+    FROM INVOICE_WITH_SUPPLIER_IDS
+);

find_manager_cycles.sql

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+USE MEMORY.DEFAULT;
+
+-- Recursive CTE to find employee-manager hierarchy loops
+WITH RECURSIVE EmployeeHierarchy (employee_id, manager_id, path) AS (
+    -- Base case: Start with employees who have a manager
+    SELECT
+        employee_id,
+        manager_id,
+        ARRAY[CAST(employee_id AS VARCHAR)] AS path
+    FROM
+        EMPLOYEE
+    WHERE
+        manager_id IS NOT NULL
+
+    UNION ALL
+
+    -- Recursive case
+    SELECT
+        eh.employee_id,
+        e.manager_id,
+        eh.path || CAST(e.employee_id AS VARCHAR)
+    FROM
+        EmployeeHierarchy eh
+    INNER JOIN
+        EMPLOYEE e
+    ON
+        eh.manager_id = e.employee_id
+    WHERE
+        NOT CONTAINS(eh.path, CAST(e.employee_id AS VARCHAR))
+)
+
+-- Final output
+SELECT
+    employee_id,
+    ARRAY_JOIN(path, ',') AS loop
+FROM
+    EmployeeHierarchy
+WHERE
+    manager_id = employee_id;

generate_supplier_payment_plans.sql

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+WITH SupplierInvoices AS (
+    SELECT
+        s.supplier_id,
+        s.name AS supplier_name,
+        SUM(i.invoice_amount) AS total_invoice_amount,
+        MAX(i.due_date) AS max_due_date
+    FROM
+        SUPPLIER s
+    INNER JOIN
+        INVOICE i
+    ON
+        s.supplier_id = i.supplier_id
+    GROUP BY
+        s.supplier_id, s.name
+),
+
+-- Generate payment schedule for each supplier
+PaymentSchedule AS (
+    SELECT
+        si.supplier_id,
+        si.supplier_name,
+        si.total_invoice_amount,
+        si.max_due_date,
+        -- Calculate the number of months until the due date
+        DATE_DIFF('MONTH', CURRENT_DATE, si.max_due_date) AS months_until_due,
+        -- Calculate the monthly payment amount (equal installments except the last one)
+        FLOOR(si.total_invoice_amount / DATE_DIFF('MONTH', CURRENT_DATE, si.max_due_date)) AS monthly_payment_amount,
+        -- Calculate the remaining amount for the last payment
+        si.total_invoice_amount - (FLOOR(si.total_invoice_amount / DATE_DIFF('MONTH', CURRENT_DATE, si.max_due_date)) * (DATE_DIFF('MONTH', CURRENT_DATE, si.max_due_date) - 1)) AS final_payment_amount
+    FROM
+        SupplierInvoices si
+),
+
+-- Generate payment dates and amounts
+Payments AS (
+    SELECT
+        ps.supplier_id,
+        ps.supplier_name,
+        ps.total_invoice_amount,
+        -- Payment amount: equal installments except the last one
+        CASE
+            WHEN n.n < ps.months_until_due - 1 THEN ps.monthly_payment_amount
+            ELSE ps.final_payment_amount
+        END AS payment_amount,
+        -- Payment date: end of each month
+        LAST_DAY_OF_MONTH(DATE_ADD('MONTH', n.n, CURRENT_DATE)) AS payment_date,
+        -- Balance to pay: total invoice amount minus cumulative payments
+        ps.total_invoice_amount - SUM(CASE
+            WHEN n.n < ps.months_until_due - 1 THEN ps.monthly_payment_amount
+            ELSE ps.final_payment_amount
+        END) OVER (PARTITION BY ps.supplier_id ORDER BY n.n) AS balance_to_pay
+    FROM
+        PaymentSchedule ps
+    CROSS JOIN
+        UNNEST(SEQUENCE(0, ps.months_until_due - 1)) AS n(n)
+)
+
+-- Final output
+SELECT
+    supplier_id,
+    supplier_name,
+    payment_amount,
+    balance_to_pay,
+    payment_date
+FROM
+    Payments
+ORDER BY
+    supplier_id, payment_date;