• “Mybatis series” advanced application of mybatis


    1. Associated query For example: since an order information can only be an order placed by one person, it is a one-to-one query starting from the order information query. If you start from the user information, it is a one to many query, because one user can place multiple orders. 1.1 one to one query […]

  • Three kinds of association mechanism of PL / SQL database execution plan


    After reading this chapter, you will learn the following: 1. What are the three associations?2. When is that suitable for which? (summary) There are three kinds of connection mechanisms Nest loop nested loop (size table)Sort merge sort merge (add index + two large tables)Hash join hash (inline) Nested loop A simple explanation is given to […]

  • Integration of springboot2. X and mongodb (10)


    Integration of springboot2. X and mongodb (10) preparation This paper introduces the integration of mongodb and spring booMongoRepositoryas well asMongoTemplateTo perform CRUD operations. Spring Boot:2.3.0.RELEASESpring Boot Data MongoDB:2.3.0.RELEASEMongoDB:4.2.6MongoDB Driver:4.0.3 Collection sample data structure to operate on (i.e., model) Department:String idString nameString descriptionArray  employees Employee:String empIdString nameint agedouble salary one to many relationships Install mongodb Mongodb […]

  • Association analysis: Python implementation of Apriori algorithm


    association analysis association analysis Association analysis is a purposeful task to find relationships in large data sets. Relationships to be found in association analysis: frequent itemsets, association rules. Support: the percentage of records in the dataset that contain the itemset. For example, if the purchase order of pencil accounts for 10% of the total order […]

  • Mongodb aggregation Pipeline & Association processing


    Associated query Exchange rate table data db.forex.insert([ { ccy: “USD”, rate: 6.91, date: new Date(“2018-12-21”) }, { ccy: “GBP”, rate: 8.72, date: new Date(“2018-08-21”) }, { ccy: “CNY”, rate: 1.0, date: new Date(“2018-10-21”) } ]) User table data > db.accounts.find().pretty() { “_id” : ObjectId(“5d80c37349f3060f1212a055”), “name” : { “first_name” : “qingquan”, “last_name” : “zeng” }, “balance” […]

  • Springmvc + mybatis + MySQL + redis (as the secondary cache)


    1、 Add the dependency required by redispom.xml <! — use redis as MySQL cache dependency to start — > <! — spring redis implementation — > <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-redis</artifactId> <version>1.6.2.RELEASE</version> </dependency> <! — redis client jar — > <dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.8.0</version> </dependency> <! — use redis as MySQL cache dependency end — > 2、 […]

  • Credential flow for SAP QM quality notification


    Credential flow for SAP QM quality notification     As shown in the figure below is a quality notification, and the document type is CC (customer complaint),   This quality notification is associated with the sales order and delivery note, as shown in the figure above. Look at the document flow of the quality notification, […]

  • MySQL data section (9) — the stored procedure implements the regular daily cleaning of expired data


    Requirement: there is an activity record form t_ Ad, every time a business initiates an activity, it will_ shake_ devices_ Some Association records are generated in the relation table. Now write a stored procedure implementation. If the activity expires, the data mark in the associated table will be deleted. 1. The code is as follows: […]

  • Technology sharing | MySQL Optimization: Join Optimization Practice


    Author: Hu Chengqing Recently, I just learned the knowledge about join optimization in teacher dingqi’s “45 lectures on MySQL real combat”, and just met a very suitable join query that needs optimization. The analysis process is a little tortuous, so I took notes. Problem SQL description The Problem SQL and execution plan are as follows: […]

  • Summarize learning ideas – S001


    There are many things involved in substratelearning, and the learning ideas of the official website are not very clear. After reading for a period of time, I will summarize the learning ideas as follows: substratelearning mainly includes two parts: rule and substratebecause substratelearning is based on the development language of rule, so we should have […]

  • Some experience of laravel in developing restful API


    Recently, I wrote API with laravel for a period of time. Let’s summarize my experience. Start APIDevelopment we can see that some websites usetokenAuthentication, some useOAuth2.0At that time, I got tangled up and saw a good saying. On the other hand, it will involve the use for othersOAuth, for your own usetokenThat’s enough At the […]

  • Learn to use mabatis


    1、 Preliminary construction and use of mbatis I am currently using idea 2019, JDK 1.8, MySQL 5.1 1. Required jar package 2. Construction structure (a).mybatis- config.xml Files are configuration running environment, data source, transaction, etc <! — mybatis configuration file is mainly written: connect to database configuration, load mapping file, after integrating spring, the configuration […]