Mongdb_crud_ Simple that example explained

First, the data operation Example explains1, data query

NOSql:db.user.find ({age:{$gt: 20}},{name,age}). Limit (5); Query the user name and age of the first five (limit (5)) records in the user collection that are greater than age>20.

Split:

1. Verify that the database data collection performs the Operation Db.user.find

2, criteria of criteria is thecondition {age:{$gt: 20}},{name,age}; We can understand that we need to pass in parameters to execute the Find function.

there are two conditions for a specific parameter age:{$GT: a result {name,age} }

3, aggregate function: After I have found the data on the basis of this data to filter;. Limit (5);

Sql:select a.name,a.age from User a WHERE a.age>20 LIMIT (0,5);

2, Data insertion

NOSql:db.user.insert ({name: "ZG", age:25,sex:1});

Split:

1. Confirm that the database data collection performs the operation

2,data data: The data that executes the operation; The data that we insert into the database

Sql:inserte into User (Name,age,sex) VALUES ("ZG", 25, 1);

Note: When we perform an insert operation without the _ID primary key field, MGDB automatically inserts a unique field as the primary key

3, Data deletion

NOSql:db.user.remove ({sex:1});

Split:

1. Confirm that the database data collection performs the operation

2,criteria Standard condition {sex:1}

Sql:delete user WHERE sex = 1;

Note: Delete the operating room Delete all data documents that meet the criteria; if we want to delete only one document record that satisfies the criteria, challenge set option

4, Data Update:

NOSql:db.user.update ({age:{$gt: 18}},{$set: {sex:2}},{multi:true});

Split:

1. Confirm that the database data collection performs the operation

2, Criteria criterion is thecondition {age:{$gt:}}

3,action operation is what we want to update {$set: {sex:2}}

4,option Options

Sql:update user SET sex = 2 WHERE age > 18;

Note: 1,MOGDB will default to update the only one qualifying document, we need to specify the Mutli option when we want to update multiple documents that meet the criteria;

2, if we need to be with the new data does not exist we can set option:{upsert:true} to add a record;

Mongdb_crud_ Simple that example explained