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Preface In many ORM frameworks, Mybatis is used by more and more Internet companies. The main reason is that Mybatis is easy to use and flexible to operate. This series is going to ask questions to learn more about Mybatis from the source layer. Put questions to The most common way to use Mybatis is to get a Mapper interface object, and the ...

Create a database first CREATE TABLE user (   id varchar(32) CHARACTER SET utf8 NOT NULL,   name varchar(50) CHARACTER SET utf8 DEFAULT NULL ,   dflag char(1) CHARACTER SET utf8 DEFAULT NULL ,   PRIMARY KEY (`id`) ) jdbc.properties configuration mysql.driver=com.mysql.jdbc.Driver mysql.url=jdbc:mysql://127.0.0.1:3306/qingmu?char ...

1. The concept of reflection has been explained in the blog in the previous section. Next, we start to analyze the business requirements logic, and then use the reflection principle to realize it;2. Description: Usually, only one database can be connected to operate data in a project, but some complex businesses will u ...

Catalog brief introduction install Component Simple use Execute native sql (not commonly used) orm use (key) Common data types Common parameters of Column Common operations (CURD) Create an instance of a mapping class Create Session session add()/ ...

I. Introduction to mybatis plug-in As for the plugins of mybatis, I think you've used them, such as the most commonly used reverse engineering, which generates model, dao, xml files and paging plugins according to the table structure. What's the working principle of these plugins, such as paging plugins? Why can it change the sql statements we ...

PT OSC execution log In the DROP COLUMN operation for table tb004 with data volume of 100000, the PT OSC tool log is: Operation, tries, wait: analyze_table, 10, 1 copy_rows, 10, 0.25 create_triggers, 10, 1 drop_triggers, 10, 1 swap_tables, 10, 1 update_foreign_keys, 10, 1 Altering `db001`.`tb004`... Creating new table... ...

Using struts to complete adding, deleting, modifying and checkingIdeas: 1. Import related pom dependencies (struts, custom tag library dependency) 2. Import the paginated tag class, z.tld, and complete the configuration of web.xml 3. dao layer to access data 4. The web layer calls the dao layer to return data to the foreground. 5. Configur ...

Counting row A database is often used to answer "how often does a certain type of data appear in a table?" The problem. For example, you may want to know how many pets you have, or how many pets each owner has, or you may want to conduct various types of census operations on your animals. Calculate the total number of animals you own ...

Requirement: query users by gender and name SQL statement: Select id, username, birthday, sex, address from 'user ` where sex = 1 and username like'% 3% ' Problems: There may be only one A.sex and username attribute, and the other is null or empty [use if tag] B. when the sex/username property is null or empty, the ...

Last article > Message flash, request extension, middleware, blueprint and context management for the introduction to Flask (1) Supplement 1. Partial function #!/usr/bin/env python # coding:utf-8 import functools def fun(a, b): print(a, b) new_fun = functools.partial(fun, "aaa") new ...