Got it. There's lots we can do here (over time) but I wouldn't mix up "D2" and "MongoDB" here π
Got it. There's lots we can do here (over time) but I wouldn't mix up "D2" and "MongoDB" here 
CREATE TABLE customers_data (
customer_id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT,
email TEXT,
phone TEXT,
gender TEXT CHECK(gender IN ('male', 'female'))
);
CREATE TABLE payments_data (
customer_id INTEGER,
transaction_date DATE,
payment_mode TEXT CHECK(payment_mode IN ('online', 'offline')),
payment_month DATE,
FOREIGN KEY (customer_id) REFERENCES customers_data(customer_id)
);


./.wrangler/state/v3/d1/<UUID>/db.sqlite instead of ./.wrangler/state/d1/DB.sqlite3wrangler d1 migration apply ...

CREATE TABLE customers_data (
customer_id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT,
email TEXT,
phone TEXT,
gender TEXT CHECK(gender IN ('male', 'female'))
);
CREATE TABLE payments_data (
customer_id INTEGER,
transaction_date DATE,
payment_mode TEXT CHECK(payment_mode IN ('online', 'offline')),
payment_month DATE,
FOREIGN KEY (customer_id) REFERENCES customers_data(customer_id)
);