查詢數組。此時你可能會使用到$all、$size。
> db.tianyc04.find()
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }
{ "_id" : 3, "fruit" : [ "orange", "banana", "peach" ] }
#通過全匹配，查詢第一行
> db.tianyc04.find({fruit:["apple", "banana", "peach"]})
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
#如果將數組中的順序顛倒，則第一行就匹配不上了。此時可以使用$all
> db.tianyc04.find({fruit:["apple", "peach", "banana"]})
> db.tianyc04.find({fruit:{$all:["apple", "peach", "banana"]}})
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
#也可以只輸入一個元素進行查詢
> db.tianyc04.find({fruit:'apple'})
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }
#如果這個元素變成了數組，mongo就會進行精確匹配。此時你可能需要使用$all進行模糊匹配：
> db.tianyc04.find({fruit:['apple']})
> db.tianyc04.find({fruit:{$all:['apple']}})
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }
#還可以按照數組中指定位置的元素進行查詢，注意數組下標的起始編號是0。
> db.tianyc04.find()
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }
{ "_id" : 3, "fruit" : [ "orange", "banana", "peach" ] }
> db.tianyc04.find({'fruit.1':'orange'})
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }
#可以按照數組長度進行查詢，只查詢數組長度為x的文檔。
> db.tianyc04.find()
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }
{ "_id" : 3, "fruit" : [ "orange", "banana", "peach" ] }
{ "_id" : 4, "fruit" : [ "apple" ] }
> db.tianyc04.find({fruit:{$size:3}})
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }
{ "_id" : 3, "fruit" : [ "orange", "banana", "peach" ] }
> db.tianyc04.find({fruit:{$size:1}})
{ "_id" : 4, "fruit" : [ "apple" ] }
>