mongodb delete if exists code example

Example 1: mongodb remove all from collection

db.collection.remove({})

Example 2: mongodb delete all documents

# To remove all documents in a collection, call the remove method with an empty query
# document {}. The following operation deletes all documents from the bios collection:

db.bios.remove( { } )

Example 3: mongodb delete document where field exists

db.users.remove({
    "$or": [
        { "firstName": { "$exists": false } },
        { "lastName": { "$exists": false } }
    ]
})