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Previously reviewed: SQL knowledge points -- insert records SQL knowledge points -- update records and delete records Basic skills of SQL (I) -- SQL and database Basic skills of SQL (II) -- basic query Basic skills of SQL (III) -- aggregation and sorting catalogue view Advantages of view Delete view Subquery scalar subquery ...

Single Line Processing Function Data processing functions are also known as one-line processing functions Features of one-line processing functions: one input corresponds to one output. As opposed to single-line processing functions, multiline processing functions. (Multi-line processing function features: multiple inputs, corresponding to o ...

1, Database design 1. Database xii_education 2. Data sheet I put the database file on Baidu network disk Link: https://pan.baidu.com/s/1e2Av81Ib14lpkhy5Feic8g Extraction code: wxih 2, Database design specification The following regulations are only for this module. For more comprehensive documents, please refer to Alibaba Java Developm ...

Mybatis is a persistence layer framework. In detail, it is a version persistence framework. It is configured through simple xml or annotations, so that the operation of the database is not so cumbersome; What is mybatis mybatis is a retrograde mapping framework, which is used to solve some problems encountered in database operation; As t ...

1, Connect database 1. Connect database 2. View a list of all databases show dbs 2, Create database, view and delete database 1. Use database, create database use Database name If you really want to create this database successfully, you must insert a data. Data cannot be directly inserted into the database. Only data can be inser ...

1. Paging plug-in MjBatis provides a plug-in mechanism so that we can enhance the function of MyBats according to our own needs. It should be noted that if you do not fully understand the operation principle of lMy Batis and the working mode of plug-ins, you'd better not use plug-ins, because it will change the working logic at the bottom of t ...

//Environment: 1. No environmental requirements text 1, Demand analysis: 1. Registration function Realize the creation of new user information: account, password, nickname and email Account number: cannot be repeated, cannot be less than 6 digits, pure number Password: no less than 6 digits Nickname: the maximum length is 6 characters a ...

pipeline operation symbol Help you carry out complex operations. Each symbol will accept documents and do corresponding operations on these documents, and then pass the results to the next pipeline until the final results appear. db.getCollection('sales').insertMany([ { "_id" : 1, "item" : "abc", "price" : 10, "quantity" : 2, "date" : ISODate ...

MySQL Master-Slave Architecture 11.1 mysql replication In production environments, if data is read and written in the same database. It is completely impossible to meet the actual needs in terms of security, high availability, or high concurrency. Therefore, data synchronization is usually done by master-slave replication to ensure data secur ...

Official documents in English: https://docs.mongodb.com/manual/ MongoDB Chinese website: MongoDB Chinese website | MongoDB Chinese documents brief introduction MongoDB is a document database designed to facilitate application development and expansion. MongoDB is a document database designed for ease of application development an ...