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1. Database table initialization Table mygoods is the commodity table, cat_id is the classification ID, goods_id is the commodity ID, and status is the current status bit of the commodity (1: valid, 0: invalid). The table creation statement is as follows: CREATE TABLE `mygoods` ( `goods_id` int(11) unsigned NOT NULL AUTO_IN ...

Getting started with mysql 01 What is a database? Classification of database The construction of mysql database mysql introduction Installation software Initialization View initial password Login with initial password & & modify initial password Modify password policy Related parameters ...

Just about to leave work, I was stopped by a development colleague. Let's see a strange problem: the query method of the same Mapper interface of Mybatis, the first return result is different from the second return result. I can't think about it! problem Talk is heap. Show me the code mapper interface definition public interface GoodsTrackMap ...

1. Execution of getById Previous As mentioned, when Mapper.java is created, it is created as a jdk proxy and the proxy processing class is MapperProxy. So when the getById method of UserMapper is executed, the invoke method is executed in MapperProxy. //MapperProxy.java @Override public Object invoke(Object proxy, Method method, Object[ ...

RocketMQ 4: filter messages 1, Filter messages 1. Tag filtration 2. Basic SQL syntax 3. Implement message producer 4. Realize message consumers 2, Transaction message 1. Transaction message sending and submission 2. Transaction compensation 3. Transaction message status 4. Create transactional pro ...

This blog is a reading note of "data analysis by Python". Please do not reprint it for other business purposes. Article directory 1. Hierarchical index 1.1 reorder and hierarchy 1.2 summary statistics by level 2. Join and merge datasets 2.1 database style DataFrame connection 2.2 merge by ...

Original link During the epidemic, did you feel sick when you were staying at home~~ The company has opened VPN, mobile computers can connect, mobile phones can work with APP test package, so walking has been at home for 11 days since entering Beijing on February 1, 2020. These two days at home telecomm ...

1. Classification of database languages DDL: Database Definition Language Used to create, modify, and delete data structures within a database, such as: 1: Create and delete databases (CREATE DATABASE || DROP DATABASE); 2: Create, modify, rename, delete tables (CREATE TABLE | ALTER TABLE | RENAME TABLE | DROP TABLE, TRUNCATE TABLE); 3: Create a ...

Summary of this section In the previous section, we realized the function of book category maintenance, so this section will mainly realize the function of book addition.   Book adding interface Use swing to implement the book adding interface. Change the code of BookAddPanel.java as follows: pa ...

One transaction Core: success or failureAtomicity Both succeed or fail Consistency The data integrity before and after the transaction should be consistent, 1000 Principle: ACID1. Atomicity Either they succeed or they fail; 2. Consistency Data integrity before and after transactions should be consiste ...