mongodb tutorial for beginners

The sixth chapter recommends 4 hours of study time 10 chaptersHow to learn: read it in detail and implement the relevant code manuallyLearning Goals : This tutorial will teach you to install node, build servers, Express, MySQL, MongoDB, write background business logic, write interfaces, and finally complete a complete project backstage, a total of 10 days is expected.Database Database management struc

($where,Array("\ $set" =$newdata));#$set: Make a node equal to a given value, similar to the $pull $pullAll $pop $inc, and slowly explain the usage later/** Result: * Original data * {"_id": ObjectId ("4d635ba2d549a02801000003"), "column_name": "col123", "Column_exp": "Xiaocai"}* was replaced by * {"_id": ObjectId ("4d635ba2d549a02801000003"), "column_name": "col123", "Column_exp": "Ggggggg", "Column_fid": 444}*///* * Replace update, overwrite original record **/$where=Array("column_name" = "co

"}}]) $last Gets the final document from the source document according to the grouping. Usually, this makes sense, along with some previous applications such as "$sort"-stage. Db.mycol.aggregate ([{$group: {_id: "$by _user", Last_url: {$last: "$url"}}]) Piping ConceptsThe UNIX command shell pipeline refers to the possibility of some inputs and outputs performing operations as input to the next command. The MongoDB aggr

, the default configuration file in/usr/local/etc under the mongod.conf # Store Data In/usr/local/var/mongodb instead of the default/data/db dbpath =/data/db # Append Logs To/usr/loc Al/var/log/mongodb/mongo.log logpath =/usr/local/var/log/mongodb/mongo.log Logappend = True # only Accept local connections bind_ip = 127.0.0.1 After editing: 1.ESC 2.

with $ 4. Cannot be included. (Point number) 5. Keys are case-sensitive and cannot be duplicated for example: {foo:1,foo:1} The naming of collections requires attention to the following points: 1. The collection name cannot be an empty string ("") 2. The collection name cannot contain the \ s character (null character), which represents the end of the collection name 3. The collection name cannot be "system." At the beginning, the prefix is reserved by the system itself 4. The collection name

": "Replsetinitiate quorum check failed because not all proposed set members responded affirmatively:192.168.176. 129:27017 failed with no route to host, 192.168.176.131:27017 failed with no route to host ","Code": 74} 5. View cluster status 　　 This entire replica set has been built. Let's test it now. The master node is responsible for the write operation, so we write on the 130 machine Repset:primary> Db.benxq.insert ({"name":"zhangsan"}) Perform read operations on 131 machines read Repset:se

processes from repeatedly inserting or updating duplicate values that result.Update if CurrentThis means that when the data is updated, an expected value is given in the update condition (this value is queried first) to prevent other processes from updating this value before the update. See an example: var myDocument = db.products.findOne( { sku: "abc123" } ); if ( myDocument ) { var oldQuantity = myDocument.quantity; var oldReordered = myDocument.reordered; var results = db.products

MongoDB basic Tutorial: CURD help class, mongodbcurd I have been studying MongoDB for the last two days, a powerful document database. My biggest feeling is that compared with traditional relational databases such as SQL or MSQ, it is much simpler to use and configure. Both cluster configuration and Failover save a lot of tedious steps, but what is the most impor

Mongodb installation and configuration tutorial, doscommand, mongodbdos Download: you can download it from the official website. The default installation directory is (C: \ mongodb \) Create a data directory Create a data DIRECTORY And a log directory under the root directory. The data directory should be placed under the root directory (for example, C: \ da

Tags: http io os ar sp file data on CTIMongoDB projection means to select only the necessary data instead of selecting the entire data for a file. If a document has 5 fields, you need to display only 3, and then select only 3 fields.Find () methodMongoDB's Find () method, which is interpreted in the MongoDB query document, accepts the second optional parameter that is the list of fields to retrieve. In MongoDB