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preface MongoDB is a database based on distributed file storage. Written in C + +. It aims to provide scalable high-performance data storage solutions for WEB applications. MongoDB is a product between relational database and non relational database. It is the most functional and relational database among non relational databases. Installati ...

background With the continuous expansion of data volume, the strengthening of analysis demand and the process of localization, the original traditional database can no longer support and complete heavy tasks. More and more data warehouses and data Lake platforms are migrating to MPP, big data and cloud original platforms. However, in thi ...

1. Introduction to Maxwell Maxwell is a MySQL real-time capture software written in Java, which is open source by Zendesk in the United States. Real time reading MySQL binary log Binlog and generates JSON format messages, which are sent to Kafka, Kinesis RabbitMQ, Redis, Google Cloud Pub/Sub, file or other platform applications. Official we ...

limit limit action Extract part of the query result set. It is usually used in paging queries How does limit work? Full usage: limit startIndex, length startIndex Is the starting subscript, length Is the length. The starting subscript starts at 0. Default usage: limit 5; This is the top five. Take out the top 5 employees in descend ...

Operation syntax of MySQL basic syntax on tables This paper summarizes the syntax of adding, deleting and modifying data in tables in MySQL and the syntax of creating tables Add data to the table (insert) Adding data to a table can be done individually or in batches Basic grammar Add single insert into Table name(field,field,fie ...

#Preface system environment: Windows 11 Enterprise Editionmysql8.0+dockervm virtual machine 1, Construction of Mysql master-slave replication 1. Pull the image docker pull mysql 2, Configuration of MYSQL main service Because I already have local mysql in 3306, the mysql port in the container is set to 33306 docker run --name mys ...

Subquery give an example Find out the name and salary of employees with higher salary than Abel Method 1: multiple queries SELECT salary `salary_abel` FROM employees WHERE last_name = 'Abel'; SELECT last_name, salary FROM employees WHERE salary > salary_abel; Mode 2 self connection SELECT e2.last_name, e2.salary FROM employees e1 , em ...

catalogue (1) Select all data (2) Modify table contents Method 1 Method 2 (3) Select a row individually (4) Select special columns (5) Classification line (6) Date calculation (7) NULL value operation (8) Pattern matching (1) Select all data select * from pet; Return: (2) Modify table contents Method 1 Delete first DELETE FR ...

Description of main functions: Administrator role View customer information, beverage management, view categories, order management and other functions. User role: Users log in and register, modify personal information, view the home page, view the classification of drinks, view hot drinks, view the details of drinks, view the shopping cart ...

Detailed explanation of Mysql constraints The blog talks about an important knowledge point in database - constraints 1, What are constraints constraint Constraints are actually constraints on the data in the table 2, Restraint effect The purpose of adding constraints in table design is to ensure that the records in the table are complete ...