【MongoDB学习笔记17】MongoDB的查询：find中的数组查询

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db.post.find()    { "_id" : ObjectId("54a530c3ff0df3732bac1681"), "id" : 2, "name" : "joe", "age" : 30, "sex" : 1, "school" : "marry" }    { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 30, "comments" : [ "test2", "test9", "test5" ], "sex" : 1, "school" : "marry" }    { "_id" : ObjectId("54a9700e1b5afd45354fd086"), "id" : 3, "test3" : 3 }    { "_id" : ObjectId("54a9701c1b5afd45354fd087"), "id" : 4, "test4" : 4 }    { "_id" : ObjectId("54a970281b5afd45354fd088"), "id" : 5, "test5" : 5 }    { "_id" : ObjectId("54a970351b5afd45354fd089"), "id" : 6, "test6" : 6 }    { "_id" : ObjectId("54a970781b5afd45354fd08a"), "id" : 7, "test7" : 7 }    { "_id" : ObjectId("54a970831b5afd45354fd08b"), "id" : 8, "test8" : 8 }    { "_id" : ObjectId("54a970901b5afd45354fd08c"), "id" : 9, "test9" : 9 }    { "_id" : ObjectId("54a9709c1b5afd45354fd08d"), "id" : 10, "test10" : 10 }    { "_id" : ObjectId("54aa8a90652d8bdfa0566d34"), "id" : 11, "test10" : 11 }    { "_id" : ObjectId("54aa97b894dcf31069b590ca"), "id" : 12, "fruit" : [ "apple", "banana", "peach" ] }    { "_id" : ObjectId("54aa97d794dcf31069b590cb"), "id" : 13, "fruit" : [ "apple", "kumquat", "orange" ] }    { "_id" : ObjectId("54aa97f294dcf31069b590cc"), "id" : 14, "fruit" : [ "cherry", "banana", "apple" ] }    >

一、$all来匹配数组中的一组元素

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> db.post.find({"fruit":{$all:["apple","banana"]}})    { "_id" : ObjectId("54aa97b894dcf31069b590ca"), "id" : 12, "fruit" : [ "apple", "banana", "peach" ] }    { "_id" : ObjectId("54aa97f294dcf31069b590cc"), "id" : 14, "fruit" : [ "cherry", "banana", "apple" ] }    >

可以看到apple和banana的顺序无关系；

二、$size来查询匹配的数组长度；

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> db.post.find({},{"id":1,"fruit":1,"_id":0})    { "id" : 2 }    { "id" : 1 }    { "id" : 3 }    { "id" : 4 }    { "id" : 5 }    { "id" : 6 }    { "id" : 7 }    { "id" : 8 }    { "id" : 9 }    { "id" : 10 }    { "id" : 11 }    { "id" : 12, "fruit" : [ "apple", "banana", "peach" ] }    { "id" : 13, "fruit" : [ "apple", "kumquat", "orange", "fruit01" ] }    {  }    > > db.post.find({"fruit":{$size:3}})    { "_id" : ObjectId("54aa97b894dcf31069b590ca"), "id" : 12, "fruit" : [ "apple", "banana", "peach" ] }    >

三、$slice操作符

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> db.post.find({"id":13})    { "_id" : ObjectId("54aa97d794dcf31069b590cb"), "id" : 13, "fruit" : [ "apple", "kumquat", "orange", "fruit01" ] }    >

返回数组前两个值   

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> db.post.find({"id":13},{"fruit":{$slice:2}})    { "_id" : ObjectId("54aa97d794dcf31069b590cb"), "id" : 13, "fruit" : [ "apple", "kumquat" ] }    >

  
返回数组的后两个值

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> db.post.find({"id":13},{"fruit":{$slice:-2}})    { "_id" : ObjectId("54aa97d794dcf31069b590cb"), "id" : 13, "fruit" : [ "orange", "fruit01" ] }    >

返回数组中间的两个值

1 2	> db.post.find({"id":13},{"fruit":{$slice:[1,2]}})    { "_id" : ObjectId("54aa97d794dcf31069b590cb"), "id" : 13, "fruit" : [ "kumquat", "orange" ] }

四、利用数组下表查询

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> db.post.find({"fruit.3":"fruit01"}) { "_id" : ObjectId("54aa97d794dcf31069b590cb"), "id" : 13, "fruit" : [ "apple", "kumquat", "orange", "fruit01" ] } >