draft: add notes + a start at some exercises

sql/00-date-basics.sql

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+-- @conn xtdb
+-- Given the following data
+-- @block
+INSERT INTO InsurancePolicies (
+    _id,
+    PolicyHolderName,
+    PolicyType,
+    PolicyDetails,
+    _valid_from,
+    _valid_to,
+    PremiumAmount,
+    CoverageAmount
+) VALUES
+    ('POL123456', 'John Doe',      'Health', {dob: DATE '1980-01-01'}, DATE '2024-01-01', DATE '2025-01-01', 1200.50, 100000.00),
+    ('POL123457', 'Jane Smith',    'Auto',   {dob: DATE '1985-02-02'}, DATE '2024-02-01', DATE '2025-02-01', 900.75,  50000.00),
+    ('POL123458', 'Alice Johnson', 'Life',   {dob: DATE '1970-03-03'}, DATE '2024-03-01', DATE '2044-03-01', 1500.00, 200000.00),
+    ('POL123459', 'Bob Brown',     'Home',   {dob: DATE '1990-04-04'}, DATE '2024-04-01', DATE '2025-04-01', 800.00,  150000.00),
+    ('POL123460', 'Charlie Davis', 'Health', {dob: DATE '1982-05-05'}, DATE '2024-05-01', DATE '2025-05-01', 1100.25, 120000.00),
+    ('POL123461', 'Diana Evans',   'Auto',   {dob: DATE '1988-06-06'}, DATE '2024-06-01', DATE '2025-06-01', 950.50,  60000.00),
+    ('POL123462', 'Evan Foster',   'Life',   {dob: DATE '1975-07-07'}, DATE '2024-07-01', DATE '2044-07-01', 1600.75, 250000.00),
+    ('POL123463', 'Fiona Green',   'Home',   {dob: DATE '1992-08-08'}, DATE '2024-08-01', DATE '2025-08-01', 850.00,  175000.00),
+    ('POL123464', 'George Harris', 'Health', {dob: DATE '1978-09-09'}, DATE '2024-09-01', DATE '2025-09-01', 1150.00, 130000.00),
+    ('POL123465', 'Hannah Jones',   'Auto',  {dob: DATE '1983-10-10'}, DATE '2024-10-01', DATE '2025-10-01', 1000.00, 70000.00);
+
+-- Here's how you get the dob:
+-- @block
+SELECT _id, (PolicyDetails).dob
+FROM InsurancePolicies
+ORDER BY _id;
+
+-- Here's how you extract the month from a date:
+-- @block
+SELECT _id, EXTRACT(MONTH FROM _valid_from)
+FROM InsurancePolicies
+ORDER BY _id;
+
+-- Here's how you calcualte the interval between two dates:
+-- @block
+SELECT _id, AGE(_valid_to, _valid_from)
+FROM InsurancePolicies
+ORDER BY _id;
+
+-- Challenge: Calculate the current age in years of each policy owner
+-- @block
+SELECT _id, 40 AS years_old
+FROM InsurancePolicies
+ORDER BY _id;
+
+-- Answer:
+-- @block
+SELECT _id, EXTRACT(YEAR FROM AGE(CURRENT_DATE, (PolicyDetails).dob)) AS years_old
+FROM InsurancePolicies
+ORDER BY _id;

sql/00-period-intersection.sql

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+-- @conn xtdb
+
+-- Let's denormalise our Policies table and create a Users table:
+-- @block
+INSERT INTO Users (_id, UserName, DateOfBirth, _valid_from) VALUES
+    (1, 'John Doe', DATE '1980-01-01', DATE '2024-01-01'),
+    (2, 'Jane Smith', DATE '1985-02-02', DATE '2024-01-01'),
+    (3, 'Alice Johnson', DATE '1970-03-03', DATE '2024-01-01'),
+    (4, 'Bob Brown', DATE '1990-04-04', DATE '2024-01-01'),
+    (5, 'Charlie Davis', DATE '1982-05-05', DATE '2024-01-01'),
+    (6, 'Diana Evans', DATE '1988-06-06', DATE '2024-01-01'),
+    (7, 'Evan Foster', DATE '1975-07-07', DATE '2024-01-01'),
+    (8, 'Fiona Green', DATE '1992-08-08', DATE '2024-01-01'),
+    (9, 'George Harris', DATE '1978-09-09', DATE '2024-01-01'),
+    (10, 'Hannah Jones', DATE '1983-10-10', DATE '2024-01-01');
+
+-- Our Policies table now looks like this:
+-- @block
+INSERT INTO Policies (
+    _id, 
+    UserId,
+    PolicyType, 
+    _valid_from, 
+    _valid_to, 
+    PremiumAmount, 
+    CoverageAmount
+) VALUES
+    ('POL123456', 1, 'Health', DATE '2024-01-01', DATE '2025-01-01', 1200.50, 100000.00),
+    ('POL123457', 2, 'Auto', DATE '2024-02-01', DATE '2025-02-01', 900.75, 50000.00),
+    ('POL123458', 3, 'Life', DATE '2024-03-01', DATE '2044-03-01', 1500.00, 200000.00),
+    ('POL123459', 4, 'Home', DATE '2024-04-01', DATE '2025-04-01', 800.00, 150000.00),
+    ('POL123460', 5, 'Health', DATE '2024-05-01', DATE '2025-05-01', 1100.25, 120000.00),
+    ('POL123461', 6, 'Auto', DATE '2024-06-01', DATE '2025-06-01', 950.50, 60000.00),
+    ('POL123462', 7, 'Life', DATE '2024-07-01', DATE '2044-07-01', 1600.75, 250000.00),
+    ('POL123463', 8, 'Home', DATE '2024-08-01', DATE '2025-08-01', 850.00, 175000.00),
+    ('POL123464', 9, 'Health', DATE '2024-09-01', DATE '2025-09-01', 1150.00, 130000.00),
+    ('POL123465', 10, 'Auto', DATE '2024-10-01', DATE '2025-10-01', 1000.00, 70000.00);
+
+-- NOTE: this would be more interesing if it was something that would affect the premium
+-- Now, let's say a user got married on the 20th May 2024, how would you update the user table?
+-- @block
+UPDATE Users FOR PORTION OF VALID_TIME FROM DATE '2024-05-20' TO NULL
+SET UserName = 'Alice Williams'
+WHERE _id = 3;
+
+-- Now let's check that:
+-- @block
+SELECT *
+FROM Users
+ORDER BY _id;
+
+-- How can we get a complete view of every time either table changed for each user?
+-- Bonus: When was each of these changes valid?
+-- Double Bonus: How would you extend this to join onto a third table? Say the Claims table?
+-- @block
+SETTING DEFAULT VALID_TIME ALL
+SELECT Users.UserName, Policies.PolicyType--, Users._valid_time * Policies._valid_time
+FROM Users
+JOIN Policies
+    ON Policies.UserId = Users._id
+WHERE Users._valid_time OVERLAPS Policies._valid_time
+ORDER BY Users._id
+
+-- Double bonus answer:
+-- @block
+SETTING DEFAULT VALID_TIME ALL
+SELECT Users.UserName, Policies.PolicyType--, Users._valid_time * Policies._valid_time * Claims._valid_time
+FROM Users
+JOIN Policies
+    ON Policies.UserId = Users._id
+JOIN Claims
+    ON Claims.PolicyId = Policies._id
+WHERE OVERLAPS(Users._valid_time, Policies._valid_time, Claims._valid_time)
+ORDER BY Users._id

sql/plan.sql

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+-- @conn xtdb
+
+-- Slide decks:
+-- - Introduction to Temporal SQL (SQL 2011)
+-- - Policy Management
+-- - Claims Management
+-- - High level benefits (synergy POC?)
+
+-- Talk about how we get data into the system
+
+-- - XTDB Features to talk about:
+--   - Schema-less
+--   - Temporal Joins
+--   - "Auto-versioning"
+
+-- Questions:
+-- - Should you include a "status" field?
+-- - Why are we "as of now" by default (non standard)?
+-- -
+
+-- Actions to explore:
+-- - Renewing a policy
+-- - Making a claim
+-- - Detecting fraud
+-- - Gap in cover (query find the gaps)
+-- - (_system_from - _valid_from) How far in the past was information entered?
+-- - Simple premium recalculation
+--   - Just based on points on license
+--   - Find out late someone got points
+--   - How much have they underpaid?
+-- - Sheduling a new policy (to avoid gaps)
+-- - Updating policy/claim details
+--   - When was each thing true (period intersection + overlaps)
+-- - No need for an audit log
+-- - Notifying policy holders of important date
+--   - time to renew, claim status changed recently
+-- - Offering discounts
+--   - Loyalty (Who has been an uninterupted customer for greater than n years?)
+-- - Compliance and regulatory reporting
+-- - Upselling (Given `Home`, `Life`, and `Health` who is missing one or more?)