mongodb更新有兩個(gè)命令：
1).update()命令
db.collection.update( criteria, objNew, upsert, multi )
criteria : update的查詢條件，類似sql update查詢內(nèi)where后面的
objNew : update的對象和一些更新的操作符（如$,$inc...）等，也可以理解為sql update查詢內(nèi)set后面的
upsert : 這個(gè)參數(shù)的意思是捆探，如果不存在update的記錄许蓖，是否插入objNew,true為插入在验，默認(rèn)是false，不插入秉颗。
multi : mongodb默認(rèn)是false,只更新找到的第一條記錄，如果這個(gè)參數(shù)為true,就把按條件查出來多條記錄全部更新巨朦。
例：
db.test0.update( { "count" : { $gt : 1 } } , { $set : { "test2" : "OK"} } ); 只更新了第一條記錄
db.test0.update( { "count" : { $gt : 3 } } , { $set : { "test2" : "OK"} },false,true ); 全更新了
db.test0.update( { "count" : { $gt : 4 } } , { $set : { "test5" : "OK"} },true,false ); 只加進(jìn)去了第一條
db.test0.update( { "count" : { $gt : 5 } } , { $set : { "test5" : "OK"} },true,true ); 全加進(jìn)去了
db.test0.update( { "count" : { $gt : 15 } } , { $inc : { "count" : 1} },false,true );全更新了
db.test0.update( { "count" : { $gt : 10 } } , { $inc : { "count" : 1} },false,false );只更新了第一條
2).save()命令
db.collection.save( x )
x就是要更新的對象，只能是單條記錄剑令。
如果在collection內(nèi)已經(jīng)存在一個(gè)和x對象相同的"_id"的記錄糊啡。mongodb就會(huì)把x對象替換collection內(nèi)已經(jīng)存在的記錄，否則將會(huì)插入x對象吁津，如果x內(nèi)沒有_id,系統(tǒng)會(huì)自動(dòng)生成一個(gè)再插入棚蓄。相當(dāng)于上面update語句的upsert=true,multi=false的情況。
例：
db.test0.save({count:40,test1:"OK"}); #_id系統(tǒng)會(huì)生成
db.test0.save({_id:40,count:40,test1:"OK"}); #如果test0內(nèi)有_id等于40的碍脏，會(huì)替換梭依，否則插入。
mongodb的更新操作符：
- $inc
用法：{ $inc : { field : value } }
意思對一個(gè)數(shù)字字段field增加value典尾，例：
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 16, "test1" : "TESTTEST", "test2" : "OK", "test3" : "TESTTEST", "test4" : "OK", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $inc : { "count" : 1 } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 17, "test1" : "TESTTEST", "test2" : "OK", "test3" : "TESTTEST", "test4" : "OK", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $inc : { "count" : 2 } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 19, "test1" : "TESTTEST", "test2" : "OK", "test3" : "TESTTEST", "test4" : "OK", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $inc : { "count" : -1 } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : "TESTTEST", "test2" : "OK", "test3" : "TESTTEST", "test4" : "OK", "test5" : "OK" }
- $set
用法：{ $set : { field : value } }
就是相當(dāng)于sql的set field = value役拴，全部數(shù)據(jù)類型都支持$set。例：
db.test0.update( { "_id" : 15 } , { $set : { "test1" : "testv1","test2" : "testv2","test3" : "testv3","test4" : "testv4" } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : "testv1", "test2" : "testv2", "test3" : "testv3", "test4" : "testv4", "test5" : "OK" }
- $unset
用法：{ $unset : { field : 1} }
顧名思義钾埂，就是刪除字段了河闰。例：
db.test0.update( { "_id" : 15 } , { $unset : { "test1":1 } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test2" : "testv2", "test3" : "testv3", "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $unset : { "test2": 0 } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test3" : "testv3", "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $unset : { "test3":asdfasf } } );
Fri May 14 16:17:38 JS Error: ReferenceError: asdfasf is not defined (shell):0
db.test0.update( { "_id" : 15 } , { $unset : { "test3":"test" } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test4" : "testv4", "test5" : "OK" }
沒看出field : 1里面的1是干什么用的，反正只要有東西就行勃教。
- $push
用法：{ $push : { field : value } }
把value追加到field里面去淤击，field一定要是數(shù)組類型才行，如果field不存在故源，會(huì)新增一個(gè)數(shù)組類型加進(jìn)去污抬。例：
db.test0.update( { "_id" : 15 } , { $set : { "test1" : ["aaa","bbb"] } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "aaa", "bbb" ], "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $push : { "test1": "ccc" } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "aaa", "bbb", "ccc" ], "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $push : { "test2": "ccc" } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "aaa", "bbb", "ccc" ], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $push : { "test1": ["ddd","eee"] } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "aaa", "bbb", "ccc", [ "ddd", "eee" ] ], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }5) $pushAll
用法：{ $pushAll : { field : value_array } }
同$push,只是一次可以追加多個(gè)值到一個(gè)數(shù)組字段內(nèi)。例：
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "aaa", "bbb", "ccc", [ "ddd", "eee" ] ], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $pushAll : { "test1": ["fff","ggg"] } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "aaa", "bbb", "ccc", [ "ddd", "eee" ], "fff", "ggg" ], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
- $addToSet
用法：{ $addToSet : { field : value } }
增加一個(gè)值到數(shù)組內(nèi)绳军，而且只有當(dāng)這個(gè)值不在數(shù)組內(nèi)才增加印机。例：
db.test0.update( { "_id" : 15 } , { $addToSet : { "test1": {$each : ["444","555"] } } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [
"aaa",
"bbb",
"ccc",
[
"ddd",
"eee"
],
"fff",
"ggg",
[
"111",
"222"
],
"444",
"555"
], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $addToSet : { "test1": {$each : ["444","555"] } } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [
"aaa",
"bbb",
"ccc",
[
"ddd",
"eee"
],
"fff",
"ggg",
[
"111",
"222"
],
"444",
"555"
], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $addToSet : { "test1": ["444","555"] } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [
"aaa",
"bbb",
"ccc",
[
"ddd",
"eee"
],
"fff",
"ggg",
[
"111",
"222"
],
"444",
"555",
[
"444",
"555"
]
], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $addToSet : { "test1": ["444","555"] } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [
"aaa",
"bbb",
"ccc",
[
"ddd",
"eee"
],
"fff",
"ggg",
[
"111",
"222"
],
"444",
"555",
[
"444",
"555"
]
], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
- $pop
刪除數(shù)組內(nèi)的一個(gè)值
用法：
刪除最后一個(gè)值：{ $pop : { field : 1 } }刪除第一個(gè)值：{ $pop : { field : -1 } }
注意，只能刪除一個(gè)值门驾，也就是說只能用1或-1射赛，而不能用2或-2來刪除兩條。mongodb 1.1及以后的版本才可以用奶是，例：
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [
"bbb",
"ccc",
[
"ddd",
"eee"
],
"fff",
"ggg",
[
"111",
"222"
],
"444"
], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $pop : { "test1": -1 } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [
"ccc",
[
"ddd",
"eee"
],
"fff",
"ggg",
[
"111",
"222"
],
"444"
], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $pop : { "test1": 1 } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "ccc", [ "ddd", "eee" ], "fff", "ggg", [ "111", "222" ] ], "test2" : [ "ccc" ], "test4" : "testv4",
"test5" : "OK" }
- $pull
用法：$pull : { field : value } }
從數(shù)組field內(nèi)刪除一個(gè)等于value值楣责。例：
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "ccc", [ "ddd", "eee" ], "fff", "ggg", [ "111", "222" ] ], "test2" : [ "ccc" ], "test4" : "testv4",
"test5" : "OK" }
db.test0.update( { "_id" : 15 } , { $pull : { "test1": "ggg" } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "ccc", [ "ddd", "eee" ], "fff", [ "111", "222" ] ], "test2" : [ "ccc" ], "test4" : "testv4", "test5"
: "OK" }
- $pullAll
用法：{ $pullAll : { field : value_array } }
同$pull,可以一次刪除數(shù)組內(nèi)的多個(gè)值。例：
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ "ccc", [ "ddd", "eee" ], "fff", [ "111", "222" ] ], "test2" : [ "ccc" ], "test4" : "testv4", "test5"
: "OK" }
db.test0.update( { "_id" : 15 } , { $pullAll : { "test1": [ "ccc" , "fff" ] } } );
db.test0.find( { "_id" : 15 } );
{ "_id" : { "floatApprox" : 15 }, "count" : 18, "test1" : [ [ "ddd", "eee" ], [ "111", "222" ] ], "test2" : [ "ccc" ], "test4" : "testv4", "test5" : "OK" }
- $ 操作符
$是他自己的意思聂沙，代表按條件找出的數(shù)組里面某項(xiàng)他自己秆麸。呵呵，比較坳口及汉【谌ぃ看一下官方的例子：
t.find()
{ "_id" : ObjectId("4b97e62bf1d8c7152c9ccb74"), "title" : "ABC", "comments" : [ { "by" : "joe", "votes" : 3 }, { "by" : "jane", "votes" : 7 } ] }
t.update( {'comments.by':'joe'}, {$inc:{'comments.$.votes':1}}, false, true )
t.find()
{ "_id" : ObjectId("4b97e62bf1d8c7152c9ccb74"), "title" : "ABC", "comments" : [ { "by" : "joe", "votes" : 4 }, { "by" : "jane", "votes" : 7 } ] }
需要注意的是，$只會(huì)應(yīng)用找到的第一條數(shù)組項(xiàng)坷随，后面的就不管了房铭。還是看例子：
t.find();
{ "_id" : ObjectId("4b9e4a1fc583fa1c76198319"), "x" : [ 1, 2, 3, 2 ] }
t.update({x: 2}, {$inc: {"x.$": 1}}, false, true);
t.find();
還有注意的是$配合$unset使用的時(shí)候驻龟，會(huì)留下一個(gè)null的數(shù)組項(xiàng)，不過可以用{$pull:{x:null}}刪除全部是null的數(shù)組項(xiàng)缸匪。例：
t.insert({x: [1,2,3,4,3,2,3,4]})
t.find()
{ "_id" : ObjectId("4bde2ad3755d00000000710e"), "x" : [ 1, 2, 3, 4, 3, 2, 3, 4 ] }
t.update({x:3}, {$unset:{"x.$":1}})
t.find()
{ "_id" : ObjectId("4bde2ad3755d00000000710e"), "x" : [ 1, 2, null, 4, 3, 2, 3, 4 ] }
{ "_id" : ObjectId("4b9e4a1fc583fa1c76198319"), "x" : [ 1, 3, 3, 2 ] }
