Find customers who signed up but never placed an order

MongoDB query compiled from plain English against the ecommerce sample schema, then verified by running it.

The compiled query

{
  "type": "aggregation",
  "collection": "customers",
  "pipeline": [
    {},
    {},
    {}
  ]
}

How the compiled query works

$lookup — joins the orders collection on _id → customerId.
$match — filters on orders.
$project — returns only name, email, status, createdAt.

Things worth knowing

This is the anti-join ("NOT EXISTS") pattern: join the related collection, then keep only the documents where nothing matched. Filtering with $ne or $exists instead is the common mistake — it does not do the same thing.

Write this in plain English instead. Mask Databases compiles the sentence above into exactly this query at build time — no AI at runtime, and you can read the output in a diff.

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Find customers who signed up but never placed an order

The compiled query

How the compiled query works

Things worth knowing

Related queries