给出一个数组,里面装了10个对象id,怎么才能一次查出这个数组里的10对象,代码怎么实现这个功能?求大神讲解,谢谢
1条回答 默认 最新
- John_like521 2017-06-14 03:38关注
查询数组。此时你可能会使用到$all、$size。
db.tianyc04.find()
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }
{ "_id" : 3, "fruit" : [ "orange", "banana", "peach" ] }#通过全匹配,查询第一行
db.tianyc04.find({fruit:["apple", "banana", "peach"]})
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }#如果将数组中的顺序颠倒,则第一行就匹配不上了。此时可以使用$all
db.tianyc04.find({fruit:["apple", "peach", "banana"]})
db.tianyc04.find({fruit:{$all:["apple", "peach", "banana"]}})
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }#也可以只输入一个元素进行查询
db.tianyc04.find({fruit:'apple'})
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }#如果这个元素变成了数组,mongo就会进行精确匹配。此时你可能需要使用$all进行模糊匹配:
db.tianyc04.find({fruit:['apple']})
db.tianyc04.find({fruit:{$all:['apple']}})
{ "_id" : 1, "fruit" : [ "apple", "banana", "peach" ] }
{ "_id" : 2, "fruit" : [ "apple", "orange", "peach" ] }#还可以按照数组中指定位置的元素进行查询,注意数组下标的起始编号是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" ] }#可以按照数组长度进行查询,只查询数组长度为x的文档。
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" ] }本回答被题主选为最佳回答 , 对您是否有帮助呢?解决 1无用
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