[canu21]

In OmniQL, JOIN isn't a clause inside another query. It's a standalone operation. You write :INNER JOIN Order User ON user_id = id, not :GET ... JOIN .... Since it starts the query and tells the engine what to do, it gets the : prefix. The rule is: anything that begins a query gets :, anything that modifies it (WHERE, ON, LIMIT) doesn't. This is actually a deliberate design choice. In SQL, JOIN lives inside a SELECT so you end up with one big statement doing multiple things. In OmniQL each : command does one thing. Flat and predictable rather than nesting clauses inside clauses. This also lets the engine translate consistently whether it outputs SQL JOINs for Postgres and MySQL or a $lookup aggregation pipeline for MongoDB. Same syntax, engine handles the rest.