插入insert
單條插入
> db.foo.insert({"bar":"baz"})
WriteResult({ "nInserted" : 1 })
批量插入
> db.foo.insert([{"_id":1},{"_id":2},{"_id":3}])
BulkWriteResult({
"writeErrors" : [ ],
"writeConcernErrors" : [ ],
"nInserted" : 3,
"nUpserted" : 0,
"nMatched" : 0,
"nModified" : 0,
"nRemoved" : 0,
"upserted" : [ ]
})
> db.foo.find()
{ "_id" : 1 }
{ "_id" : 2 }
{ "_id" : 3 }
>
如果在執行批量插入的過程中有一個文檔插入失敗，那么在這個文檔之前的所有文檔都會插入成功，之后的所有全部失敗。
> db.foo.insert([{"_id":10},{"_id":11},{"_id":10},{"_id":12}])
BulkWriteResult({
"writeErrors" : [
{
"index" : 2,
"code" : 11000,
"errmsg" : "E11000 duplicate key error collection: test.foo index: _id_ dup key: { : 10.0 }",
"op" : {
"_id" : 10
}
}
],
"writeConcernErrors" : [ ],
"nInserted" : 2,
"nUpserted" : 0,
"nMatched" : 0,
"nModified" : 0,
"nRemoved" : 0,
"upserted" : [ ]
})
> db.foo.find()
{ "_id" : 10 }
{ "_id" : 11 }
>
刪除文檔
remove
remove函數接受一個查詢文檔作為參數。符合條件的文檔才被刪除。刪除數據是永久性的，不能撤銷，也不能恢復。
> db.foo.remove() 2016-12-15T19:50:31.721+0800 E QUERY [thread1] Error: remove needs a query : DBCollection.prototype._parseRemove@src/mongo/shell/collection.js:406:1 DBCollection.prototype.remove@src/mongo/shell/collection.js:433:18 @(shell):1:1 > db.foo.remove({"_id":10}) WriteResult({ "nRemoved" : 1 }) > db.foo.find() { "_id" : 11 } >
drop
要清空整個集合，那么使用drop直接刪除集合會更快。代價是：不能指定任何限定條件。整個集合都被刪除，所有元數據都不見了。
> for(var i=0;i<1000000;i++){ ... db.tester.insert({"foo":"bar","baz":i,"z":10-i}) ... } WriteResult({ "nInserted" : 1 }) > db.tester.find() { "_id" : ObjectId("58528543b049609a5fa74f7c"), "foo" : "bar", "baz" : 0, "z" : 10 }
......
Type "it" for more > db.tester.drop()//插入一百萬條數據，使用drop刪除,只需1ms true >
更新文檔update
Update有兩個必須參數：
一是查詢文檔，用於定位需要更新的目標文檔
二是修改器文檔，用於說明要找到的文檔進行哪些修改
更新操作是不可分割的：若是兩個更新同時發生，先到達服務器的先執行，接着執行另一個。
db.foo.insert({ ... "name":"yyb", ... "friends":32, ... "enemies":2 ... }) WriteResult({ "nInserted" : 1 }) > db.foo.update({"name":"yyb"},{"name":"joe"})//將yyb這個文檔修改成{“name”:“joe”} WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.foo.find() { "_id" : ObjectId("58528a2bb049609a5fb691bc"), "name" : "joe" } >
文檔替換
用一個新文檔完全替換匹配的文檔，這適合大規模模式遷移的情況。
db.user.insert({ ... ... "name":"joe", ... ... "friends":32, ... ... "enemies":2 ... ... }) WriteResult({ "nInserted" : 1 }) //將上面這個文檔的后兩個字段移到子文檔為realtionships中 > var joe=db.user.findOne({"name":"joe"}) > joe.relationships={"friends":joe.friends,"enemies":joe.enemies}; { "friends" : 32, "enemies" : 2 } > delete joe.friends true > delete joe.enemies true > db.user.update({"name":"joe"},joe); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.user.find() { "_id" : ObjectId("58529188b049609a5fb691bf"), "name" : "joe", "relationships" : { "friends" : 32, "enemies" : 2 } } >
常見的錯誤是查詢條件匹配到了多個文檔，然后更新時由於第二個參數的存在就產生重復的 _id 值。數據庫會拋出異常。
> db.user.find() { "_id" : ObjectId("585295e3b049609a5fb691c5"), "name" : "yyb", "age" : 21 } { "_id" : ObjectId("585295e3b049609a5fb691c6"), "name" : "yyb", "age" : 30 } { "_id" : ObjectId("585295e3b049609a5fb691c7"), "name" : "yyb", "age" : 40 } > joe=db.user.findOne({"name":"yyb","age":30}) { "_id" : ObjectId("585295e3b049609a5fb691c6"), "name" : "yyb", "age" : 30 } > joe.age++; 30 > db.user.update({"name":"yyb"},joe) WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0, "writeError" : { "code" : 16837, "errmsg" : "The _id field cannot be changed from {_id: ObjectId('585295e3b049609a5fb691c5')} to {_id: ObjectId('585295e3b049609a5fb691c6')}." } }) >
使用修改器
使用原子性的更新修改器，指定對文檔的某些字段進行更新。更新修改器是種特殊的鍵，用來指定復雜的更新操作，比如修改、添加或者刪除鍵，還可能是操作數組或者內嵌文檔。
> db.user.find() { "_id" : ObjectId("585295e3b049609a5fb691c5"), "name" : "yyb", "age" : 21 } { "_id" : ObjectId("585295e3b049609a5fb691c6"), "name" : "yyb", "age" : 30 } { "_id" : ObjectId("585295e3b049609a5fb691c7"), "name" : "yyb", "age" : 40 } > db.user.update({"name":"yyb"},{$inc:{"age":5}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find({"name":"yyb"}) { "_id" : ObjectId("585295e3b049609a5fb691c5"), "name" : "yyb", "age" : 26 } { "_id" : ObjectId("585295e3b049609a5fb691c6"), "name" : "yyb", "age" : 30 } { "_id" : ObjectId("585295e3b049609a5fb691c7"), "name" : "yyb", "age" : 40 } >
明明匹配3條，卻只改了一條。原來MongoDB默認只會更新匹配的第一條，如果要更新多條，還得指定參數。
使用修改器時，_id的值不能改變。（整個文檔替換時可以改變“_id”）
$set與$unset
用來指定一個字段的值。如果這個字段不存在，則創建它。
> db.user.insert({ ... "name":"yyb", ... "age":20, ... "sex":"male", ... "location":"cd"}) WriteResult({ "nInserted" : 1 }) >> db.user.update({"name":"yyb"},{"$set":{"email":"123@qq.com"}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.user.find().pretty() { "_id" : ObjectId("58529e66b049609a5fb691c9"), "name" : "yyb", "age" : 20, "sex" : "male", "location" : "cd", "email" : "123@qq.com" } >
用 $set 甚至可以修改鍵的類型。用 $unset 可以將鍵完全刪除。
> db.user.update( ... ... {"name":"yyb"}, ... ... {"$set":{"email":["xx@qq.com","xl@sina.com"]}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.user.find().pretty() { "_id" : ObjectId("58529e66b049609a5fb691c9"), "name" : "yyb", "age" : 20, "sex" : "male", "location" : "cd", "email" : [ "xx@qq.com", "xl@sina.com" ] } > db.user.update({"name":"yyb"},{"$unset":{"email":1}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.user.find().pretty() { "_id" : ObjectId("58529e66b049609a5fb691c9"), "name" : "yyb", "age" : 20, "sex" : "male", "location" : "cd" }
也可以用 $set 修改內嵌文檔：
{ "_id" : ObjectId("5853e17ff7720722b4ded850"), "title" : "a blog post", "content" : "...", "author" : { "name" : "yyb", "email" : "aaa@sina.com" } } > db.blog.update( ... {"author.name":"yyb"}, ... {"$set":{"author.name":"joe"}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.blog.findOne() { "_id" : ObjectId("5853e17ff7720722b4ded850"), "title" : "a blog post", "content" : "...", "author" : { "name" : "joe", "email" : "aaa@sina.com" } }
增加、刪除、修改鍵時，應該使用$開頭的修改器，否則可能會將整個文檔替換掉。
$inc
$inc 用來增加已有鍵的值，或者該鍵不存在那就創建一個。對於更新分析數據、因果關系、投票或者其他有變化數值的地方很方便。
> db.games.insert({"games":"pinball","user":"joe"})
WriteResult({ "nInserted" : 1 })
> db.games.update({"games":"pinball"},{"$inc":{"score":50}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.games.findOne()
{
"_id" : ObjectId("5853e517f7720722b4ded851"),
"games" : "pinball",
"user" : "joe",
"score" : 50
}
> db.games.update({"games":"pinball"},{"$inc":{"score":10000}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.games.findOne()
{
"_id" : ObjectId("5853e517f7720722b4ded851"),
"games" : "pinball",
"user" : "joe",
"score" : 10050
}
>
$inc 就是專門用來增減數字的。且只能用於整型、長整型或者雙精度浮點型的值。其他類型的數據會操作失敗。
> db.foo.insert({"count":"1"})
WriteResult({ "nInserted" : 1 })
> db.foo.update({},{"$inc":{"count":1}})
WriteResult({
"nMatched" : 0,
"nUpserted" : 0,
"nModified" : 0,
"writeError" : {
"code" : 16837,
"errmsg" : "Cannot apply $inc to a value of non-numeric type. {_id: ObjectId('5853e73df7720722b4ded853')} has the field 'count' of non-numeric type String"
}
})
>
$inc 鍵的值必須為數字”，不能使用字符串、數組或者其他非數字的值。要修改其他類型，應該使用 $set 或者數字修改器。
> db.foo.insert({"count":1})
WriteResult({ "nInserted" : 1 })
> db.foo.update({},{"$inc":{"count":"5"}})
WriteResult({
"nMatched" : 0,
"nUpserted" : 0,
"nModified" : 0,
"writeError" : {
"code" : 14,
"errmsg" : "Cannot increment with non-numeric argument: {count: \"5\"}"
}
})
>
數組修改器
$push
$push 添加元素。如果數組已經存在，會向已有的數組末尾加入一個元素，要是沒有就創建一個新的數組。
> db.blog.post.findOne() { "_id" : ObjectId("5853ea01f7720722b4ded855"), "title" : "a blog post", "content" : "..." } > db.blog.post.update( ... {"title":"a blog post"}, ... {"$push":{"comments":{"name":"joe","email":"joe@qq.com","content":"nice post"}}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.blog.post.findOne() { "_id" : ObjectId("5853ea01f7720722b4ded855"), "title" : "a blog post", "content" : "...", "comments" : [ { "name" : "joe", "email" : "joe@qq.com", "content" : "nice post" } ] } >
> db.blog.post.update( ... {"title":"a blog post"}, ... {"$push":{"comments":{"name":"bob","email":"bob@sina.com","content":"good post."}}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.blog.post.findOne() { "_id" : ObjectId("5853ea01f7720722b4ded855"), "title" : "a blog post", "content" : "...", "comments" : [ { "name" : "joe", "email" : "joe@qq.com", "content" : "nice post" }, { "name" : "bob", "email" : "bob@sina.com", "content" : "good post." } ] } >
$each
可以將它應用在一些比較復雜的數組操作中。使用 $each 子操作符，可以通過一次 $push 操作添加多個值。
比如：下面將三個新元素添加到數組中。如果指定的數組中只包含一個元素，那么等同於和沒有使用“$each”的普通的“$push”操作。
db.stock.ticket.insert({"_id":"goog"})
WriteResult({ "nInserted" : 1 })
> db.stock.ticket.update(
... ... ... {"_id":"goog"},
... ... ... {"$push":{"hourly":{"$each":[562.776,562.790,559.123]}}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.stock.ticket.findOne()
{ "_id" : "goog", "hourly" : [ 562.776, 562.79, 559.123 ] }
要實現上面的操作，下面方法也可以。
db.stock.ticket.update( ... ... ... ... ... {"_id":"goog"}, ... ... ... ... ... {"$set":{"hourly":[562.776,562.790,559.123]}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.stock.ticket.findOne() { "_id" : "goog", "hourly" : [ 562.776, 562.79, 559.123 ] }
而下面這樣是不行的
db.stock.ticket.update( ... ... ... ... {"_id":"goog"}, ... ... ... ... {"$push":{"hourly":[562.776,562.790,559.123]}}) WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) > db.stock.ticket.findOne() { "_id" : "goog", "hourly" : [ [ 562.776, 562.79, 559.123 ] ] }