数据
以下是 inventory 集合的数据
{ "_id": 1, "dept": "A", "item": { "sku": "111", "color": "red" }, "sizes": [ "S", "M" ] }
{ "_id": 2, "dept": "A", "item": { "sku": "111", "color": "blue" }, "sizes": [ "M", "L" ] }
{ "_id": 3, "dept": "B", "item": { "sku": "222", "color": "blue" }, "sizes": "S" }
{ "_id": 4, "dept": "A", "item": { "sku": "333", "color": "black" }, "sizes": [ "S" ] }
db.inventory.distinct(“dept”) //获取dept字段的不重复值
结果：[“A”,”B”]
db.inventory.distinct(“item.sku”) //获取item子字段sku的不重复值
结果：[“111”,”222”,”333”]
db.inventory.distinct(“sizes”) //获取数组格式字段的不重复值
结果：[“M”,”S”,”L”]
db.inventory.distinct(“item.sku”,{dept:”A”}) //满足dept为A数据的item字段的子字段的不重复值
结果：[“111”,”333”]
