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tkMapper usage and demo demonstration 1. Realization Law of Dao Layer - Preface Entity classes correspond to data tables and are regular - they can be generated as long as the structure of the data table is known. A single word equals a single word, and multiple word fields are the hump nomenclature.The methods defined in the DAO interfaces o ...

catalogue 1. Multi table query 1.1 many to one (1)   The first way is to query through linked list. (2) The second way is through nested query. ---- two queries.   one point two   One to many 2. Dynamic SQL (1) if with where   (2)   [choose when otherwise] and where   (3)set tag --- modify some fields ...

1, Dynamic SQL Official website: https://mybatis.org/mybatis-3/zh/dynamic-sql.html Dynamic SQL is one of the powerful features of MyBatis. If you have used JDBC or other similar frameworks, you should be able to understand how painful it is to splice SQL statements according to different conditions. For example, when splicing, make sure you c ...

preface Tip: Here you can add the general contents to be recorded in this article: For example, with the continuous development of artificial intelligence, machine learning technology is becoming more and more important. Many people have started learning machine learning. This paper introduces the basic content of machine learning. Ti ...

1, Tool preparation       1.maven   Version maven-3.8.2       2.tomcat   Version tomcat-8.5.65       3. Database   Version 8.0.24       4. The database source is c3p0   Version 0.9.5.2 2, Database construction statement Note: the following sql statement ...

MyBatis connects to Mysql to complete addition, deletion, modification and query 1. Step 1: create a SpringBoot project Select related dependencies Note: if you forget to import the related dependencies: you can import them manually. Search the name of the related jar in the link below maven warehouse Step 2: create database tables accordin ...

Preparation for multi table query: three tables are created. Previously used user table, newly created role table, account table, user_role table. The specific parameters in the table are as follows: user table (mainly the header, which is filled in by itself): role table: account table: user_role table: After these classes are created, r ...

1, Mybatis annotation development single table operation 1.1 common notes of mybatis In recent years, annotation development has become more and more popular. Mybatis can also use annotation development, so that we can reduce the writing of Mapper Mapping file. We first learn about some basic CRUD, and then learn about complex mapping ...

Question type choice question Program reading questions Program error correction Procedural blank filling Programming problem Master the meaning of common coordinate dependency, such as web, hot deployment, etc <dependencies> <dependency> <groupId>Project group ID</groupId> <artifactId>Project id ...

1. Syntax of mapping file XXMapper.xml: <mapper namespace="cn.kgc.mspper.UserMapper"> <select id=" findCount " ... ...... </select> </mapper> 1.1 namespace: namespace The name of a namespace must have the same name as an interface 1.2 id: unique identifier in namespace** The method in the interface corresponds to ...