MongoDB CRUD Operations / MongoDB的增删改查操作

###Insert Documents

1> Insert a Document

1.1> Create a document. Define a variable document that holds a document to insert.

document=({"user_id" : "chen","password" :"chen123" ,"DOB" :
	"02/03/1992" ,"education" :"M.C.S." , "profession" : "DEVELOPER"})

1.2> Insert the document. Pass the variable document to the db.collection.insert() to perform an insert.

db.myinfo.insert(document);

2> Directly Insert without Document.

db.myinfo.insert({"user_id" : "hao","password" :"hao123" ,"DOB" : "02/12/1990" ,
	"education" :"M.C.A." , "profession" : "Software consultant"});

###Modify Documents

MongoDB can use update() function to modify data.

db.collection.update( criteria, objNew, upsert, multi )

criteria : update conditions, similar to the statements after where in sql update.

objNew : update’s objects or some update operations ($,$inc…), may ragard as the statements after set in sql update.

upsert : if the record doesn’t exist, if you want to insert this new record, true is insert, default is false, don’t insert.

multi : defaust is false, only update the first record it found. if it is true, update all records meet the conditions.

db.myinfo.update({"user_id" : "hao"},{"user_id" : "hui","password" :"hui123" ,
	"DOB" : "06/06/1990" ,"education" :"M.E.B." , "profession" : "MARKETING"});

###Query Documents

Select all documents in a collection

db.myinfo.find({}); // or
db.myinfo.find();

which is similar to SQL statement

Select * from myinfo;

Select the documents which “education” is “M.C.S”

db.myinfo.find({"education":"M.C.S."});

which is similar to SQL statement

Select * from myinfo where education="M.C.S.";

Conditional operator:

(>) - $gt

(<) - $lt

(>=) - $gte

(<= ) - $lte

For example 1,

db.testtable.find({age : {$gt : 22}})

is similar to SQL statement

Select * from testtable where age >22;

Example 2,

db.testtable.find({age : {$lt :24, $gt : 17}})

is similar to SQL statement

Select * from testtable where age > 17 and age <24;

limit() accept a integer parameter, to define the number of records selected from MongoDB

db.COLLECTION_NAME.find().limit(NUMBER)

skip() to ignore the number of records

db.COLLECTION_NAME.find().limit(NUMBER).skip(NUMBER)

sort(), 1 is ascending, and -1 is descending

db.COLLECTION_NAME.find().sort({KEY:1})

###Remove Documents

Use remove() if you want to delete record where “user_id” = “chen” in “myinfo”, you may use,

db.myinfo.remove( { "user_id" : "chen" } );

Delete all data if you want to delete all records in “myinfo”, you may use,

db.myinfo.remove({});

Use drop() to delete collections if you want to delete the whole “myinfo”, including data and documents, you may use,

db.myinfo.drop();

Use dropDatabase() to delete database if you want to delete the whole database, you may use,

db.dropDatabase()

###数据插入

###数据修改

###数据查询

###数据删除

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