query syntax
db.collection.find(query, projection)
- query : optional, use query operators to specify query conditions
- projection : optional, use the projection operator to specify the returned key. When querying, all key values in the document are returned, just omit this parameter (default omission).
example
1. Query all fields by default
db.getCollection('user').find({
name: 'Tom'})
{
"_id" : "5b28c9e4-29d8-4b33-88d8-e74596b86dc7",
"name" : "Tom",
"age" : 20,
"birthday" : "2000-10-01 00:00:00"
}
2. Query the specified field
db.getCollection('user').find({
name: 'Tom'}, {
name: 1, age: 1})
{
"_id" : "5b28c9e4-29d8-4b33-88d8-e74596b86dc7",
"name" : "Tom",
"age" : 20
}