db.collection.update(query, update)
整体替换。
> db.user.find()
{
"_id" : 1, "username" : "a" }
{
"_id" : 2, "username" : "b" }
// update默认是整体替换掉满足条件的文档而不是单独的修改指定字段的值
> db.user.update({
"_id": 1}, {
"age": 30})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "age" : 30 }
{
"_id" : 2, "username" : "b" }
// update(query, update) : 默认修改满足条件的第一条文档
> db.user.find()
{
"_id" : 1, "username" : "a" }
{
"_id" : 2, "username" : "a" }
> db.user.update({
"username": "a"}, {
"username": "aa"})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "aa" }
{
"_id" : 2, "username" : "a" }
db.collection.update(query, update, insertOrUpdate)
// 不存在则添加
> db.user.find()
> db.user.update({
"_id": 1}, {
"username": "addOrUpdate"}, true)
WriteResult({
"nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "addOrUpdate" }
// 存在则更新
> db.user.update({
"_id": 1}, {
"username": "Update"}, true)
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "Update" }
修饰器
$set
局部修改，修改指定字段的值。
// 使用 $set修改器 修改指定字段, 当字段不存在时会创建并赋值
> db.user.find()
{
"_id" : 1, "username" : "a" }
{
"_id" : 2, "username" : "b" }
// 字段存在则修改，不存在则添加字段
> db.user.update({
"_id": 1}, {
"$set": {
"username": "aa", "age": 30}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "aa", "age" : 30 }
{
"_id" : 2, "username" : "b" }
db.collection.update(query, update, insertOrUpdate, multiUpdate)
批量更新只适用于局部替换，不能使用全局覆盖。
> db.user.find()
{
"_id" : 1, "username" : "a" }
{
"_id" : 2, "username" : "a" }
// 批量 局部更新
> db.user.update({
"username": "a"}, {
"$set": {
"username": "aaa"}}, false, true)
WriteResult({
"nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })
> db.user.find()
{
"_id" : 1, "username" : "aaa" }
{
"_id" : 2, "username" : "aaa" }
$unset
用于删除字段。
// 删除age字段
> db.user.update({
"_id": 1}, {
"$unset": {
"age": 1}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "aa" }
{
"_id" : 2, "username" : "b" }
$inc
用于递增或者递减某个值，值为整数表示递增，值为负数表示递减。
> db.user.find()
{
"_id" : 1, "age" : 29 }
{
"_id" : 2, "age" : 30 }
> db.user.update({
_id: 1}, {
"$inc": {
"age": 2}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "age" : 31 }
{
"_id" : 2, "age" : 30 }
> db.user.update({
_id: 1}, {
"$inc": {
"age": -2}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "age" : 29 }
{
"_id" : 2, "age" : 30 }
$push
向数组字段的尾部添加一个元素，如果字段不存在则创建。
> db.user.find()
{
"_id" : 1, "username" : "aa" }
{
"_id" : 2, "username" : "b" }
// 文档不存在hobby字段就添加，类型为数组
> db.user.update({
"_id": 1}, {
"$push": {
"hobby": "money"}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "aa", "hobby" : [ "money" ] }
{
"_id" : 2, "username" : "b" }
// 文档hobby存在字段，就向数组尾部添加元素
> db.user.update({
"_id": 1}, {
"$push": {
"hobby": "xiaojiejie"}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "aa", "hobby" : [ "money", "xiaojiejie" ] }
{
"_id" : 2, "username" : "b" }
$push + $each
向数组字段的尾部一次性添加多个元素。
> db.user.find()
{
"_id" : 1, "username" : "a" }
{
"_id" : 2, "username" : "b" }
// 一次性向数组字段的尾部添加多个元素
> db.user.update({
"_id": 1}, {
"$push": {
"hobby": {
"$each": ["money", "xiaojiejie"]}}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "a", "hobby" : [ "money", "xiaojiejie" ] }
{
"_id" : 2, "username" : "b" }
$addToSet
想数组尾部添加一个不存在的元素，如果存在则不添加。
> db.user.find()
{
"_id" : 1, "username" : "a" }
{
"_id" : 2, "username" : "b" }
// 第一次添加成功
> db.user.update({
"_id": 1}, {
"$addToSet": {
"hobby": "money"}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "a", "hobby" : [ "money" ] }
{
"_id" : 2, "username" : "b" }
// 第二次添加失败
> db.user.update({
"_id": 1}, {
"$addToSet": {
"hobby": "money"}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 0 })
> db.user.find()
{
"_id" : 1, "username" : "a", "hobby" : [ "money" ] }
{
"_id" : 2, "username" : "b" }
$pop
弹出数组的头部元素或尾部元素： -1：头部，1：尾部。
> db.user.find()
{
"_id" : 1, "username" : "a", "hobby" : [ "money", "xiaojiejie", "dog" ] }
{
"_id" : 2, "username" : "b" }
> db.user.update({
"_id": 1}, {
"$pop": {
"hobby": 1}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "a", "hobby" : [ "money", "xiaojiejie" ] }
{
"_id" : 2, "username" : "b" }
>
$pull
删除数组中的指定的值。
> db.user.find()
{
"_id" : 1, "username" : "a", "hobby" : [ "money", "xiaojiejie", "dog" ] }
{
"_id" : 2, "username" : "b" }
// 删除指定的元素
> db.user.update({
"_id": 1}, {
"$pull": {
"hobby": "xiaojiejie"}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1, "username" : "a", "hobby" : [ "money", "dog" ] }
{
"_id" : 2, "username" : "b" }
使用下标修改数组中指定的元素
> db.user.insert({
"_id" : 1, "addresses" : [ {
"city" : "shanghai", "area" : "pudong" }, {
"city" : "beijing", "area" : "chaoyang" } ] })
// 修改addresses字段中的第二个元素中的area字段的值
> db.user.update({
"_id": 1}, {
"$set": {
"addresses.1.area": "dongcheng"}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find()
{
"_id" : 1,
"addresses" : [
{
"city" : "shanghai", "area" : "pudong" },
{
"city" : "beijing", "area" : "dongcheng" }
]
}
// $ 表示满足条件所对应的下标
> db.user.update({
"addresses.city": "shanghai"}, {
"$set": {
"addresses.$.area": "Pu Dong"}})
WriteResult({
"nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.user.find().pretty()
{
"_id" : 1,
"addresses" : [
{
"city" : "shanghai",
"area" : "Pu Dong"
},
{
"city" : "beijing",
"area" : "dongcheng"
}
]
}
db.collection.findAndModify({ “query”: xxx, “update”: xxx)
findAndModify : 查找满足添加的值并返回，并且修改满足条件的第一条文档。
> db.user.find()
{
"_id" : 1, "username" : "a" }
{
"_id" : 2, "username" : "a" }
> db.user.findAndModify({
"query": {
"username": "a"}, "update": {
"username": "aa"}})
{
"_id" : 1, "username" : "a" }
> db.user.find()
{
"_id" : 1, "username" : "aa" }
{
"_id" : 2, "username" : "a" }
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