{Complexity}

Theta Style:
SELECT i.order_id, p.product_id, p.name, p.desc
FROM CustomerItem i, Product p
WHERE i.product_id = p.product_id
AND i.order_id = 84463;

ANSI Style:
SELECT i.order_id, p.product_id, p.name, p.desc
FROM CustomerItem i
INNER JOIN Product p ON i.product_id = p.product_id
WHERE i.order_id = 84463;

Sometimes, it’s hard to realized whether there is other style of SQL. Obviously there are two different SQL style. theta is older and more obscure but many people still use it.