mongoDB更新详解

向右看齐 2022-08-06 06:26 202阅读 0赞

mongodb更新有两个命令：  
  
**1).update()命令**  
  
db.collection.update( criteria, objNew, upsert, multi )  
  
criteria : update的查询条件，类似sql update查询内where后面的  
objNew   : update的对象和一些更新的操作符（如$,$inc...）等，也可以理解为sql update查询内set后面的  
upsert   : 这个参数的意思是，如果不存在update的记录，是否插入objNew,true为插入，默认是false，不插入。  
multi    : mongodb默认是false,只更新找到的第一条记录，如果这个参数为true,就把按条件查出来多条记录全部更新。  
  
例：  
db.test0.update( \{ "count" : \{ $gt : 1 \} \} , \{ $set : \{ "test2" : "OK"\} \} ); 只更新了第一条记录  
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 ); 只加进去了第一条  
db.test0.update( \{ "count" : \{ $gt : 5 \} \} , \{ $set : \{ "test5" : "OK"\} \},true,true ); 全加进去了  
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 );只更新了第一条  
  
**2).save()命令**  
  
db.collection.save( x )  
  
x就是要更新的对象，只能是单条记录。  
  
如果在collection内已经存在一个和x对象相同的"\_id"的记录。mongodb就会把x对象替换collection内已经存在的记录，否则将会插入x对象，如果x内没有\_id,系统会自动生成一个再插入。相当于上面update语句的upsert=true,multi=false的情况。  
  
例：  
db.test0.save(\{count:40,test1:"OK"\}); \#\_id系统会生成  
db.test0.save(\{\_id:40,count:40,test1:"OK"\}); \#如果test0内有\_id等于40的，会替换，否则插入。  
  
  
mongodb的更新操作符：  
  
**1) $inc**  
  
用法：\{ $inc : \{ field : value \} \}  
  
意思对一个数字字段field增加value，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" \}  
  
  
**2) $set**  
  
用法：\{ $set : \{ field : value \} \}  
  
就是相当于sql的set field = value，全部数据类型都支持$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" \}  
  
**3) $unset**  
  
用法：\{ $unset : \{ field : 1\} \}  
  
顾名思义，就是删除字段了。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" \}  
  
没看出field : 1里面的1是干什么用的，反正只要有东西就行。  
  
  
**4) $push**

用法：{ $push : { field : value } }
    
    把value追加到field里面去，field一定要是数组类型才行，如果field不存在，会新增一个数组类型加进去。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个值到一个数组字段内。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" \}  
  
**6)  $addToSet**

用法：{ $addToSet : { field : value } }
 
 增加一个值到数组内，而且只有当这个值不在数组内才增加。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" }
 
 
 7) $pop
 
 删除数组内的一个值
 
 用法：
 删除最后一个值：{ $pop : { field : 1 } }

删除第一个值：{ $pop : { field : -1 } }
 
 注意，只能删除一个值，也就是说只能用1或-1，而不能用2或-2来删除两条。mongodb 1.1及以后的版本才可以用，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" }
 
 8) $pull
 
 用法：$pull : { field : value } }
 
 从数组field内删除一个等于value值。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" }
 
 9) $pullAll
 
 用法：{ $pullAll : { field : value_array } }
 
 同$pull,可以一次删除数组内的多个值。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" }
 
 
 10) $ 操作符
 
 $是他自己的意思，代表按条件找出的数组里面某项他自己。呵呵，比较坳口。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，$只会应用找到的第一条数组项，后面的就不管了。还是看例子：
 
 > t.find();
 { "_id" : ObjectId("4b9e4a1fc583fa1c76198319"), "x" : [ 1, 2, 3, 2 ] }
 > t.update({x: 2}, {$inc: {"x.$": 1}}, false, true);
 > t.find();
 
 还有注意的是$配合$unset使用的时候，会留下一个null的数组项，不过可以用{$pull:{x:null}}删除全部是null的数组项。例：
 > t.insert({x: [1,2,3,4,3,2,3,4]})
 > t.find()
 { "_id" : ObjectId("4bde2ad3755d00000000710e"), "x" : [ 1, 2, 3, 4, 3, 2, 3, 4 ] }
 > t.update({x:3}, {$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 ] }