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JDBC connection mode and steps 1. Register driver Diver dirver =new com.mysql.jdbc.Diver(); In this way, the interface of Sun company is implemented first. mysql manufacturers implement it according to the interface. Dirver on the left is the interface, and interface implementation classes on the right DiverManager.registerDirver(dirver); ...

preface When creating a table, you can add corresponding constraints to the fields of the table. The purpose of adding constraints is to ensure the legitimacy, validity and integrity of the data in the table. Common constraints nameexplainNon NULL constraint (not null)The field of the constraint cannot be NULLUnique constraintConstrained ...

Hi Wen Ledao's large TV series "when is davinci updated" finally came to an end in the early autumn of 21 years, followed by the official release of the popular new product datart (Digital Art). This year, we can see that there are many such people in the group     So..   And so on..   What else?   Wha ...

MySQL advanced - Notes - 01 Video of this article: Dark horse MySQL advanced 1, MySQL architecture 1-1 overview of MySQL architecture The entire MySQL Server consists of the following components: Connection Pool: Connection Pool componentManagement services & Utilities: management services and tools componentsSQL interface: SQL i ...

@[TOC] nodeJS express creates a server and operates the mysql database (personal study notes) 1, Initialization 1. Create project 1.1 create folders and initialize package management files npm init -y 1.2 installing express npm i express@4.17.1 1.3 create the app.js file in the root directory file as the entry file of the whole project ...

mysql Foundation essential information All query statements must be; End with a semicolon Display database show databases; Use database use database_name; Table showing the database show tables; Display column information of database table show columns from table_name; Retrieve data SELECT -- Retrieve all data from multiple columns ...

MySQL query Cascade: On delete cascade on update csacde update cascade When deleting data: you need to delete the foreign key table before deleting the primary key table When entering data: enter the primary key first, and then enter the foreign key When the master table data is deleted, the master table data changes with the slave table, and ...

1, Foreword Recently, we are using Sqoop+Jekins to realize the data transfer between mysql and hive database. It mainly uses the Import command of sqoop to import mysql data into hive, and uses the export command to export hive data to mysql. Jekins plays a regular role, executing sh scripts regularly and synchronizing once a day. Relevant ...

1. Overview of Mybatis 1.1 Mybatis concepts MyBatis was originally an open source project for apache, iBatis, which was migrated to google code by apache software foundation in 2010 and renamed MyBatis. Migrated to Github in November 2013. The term iBATIS, derived from a combination of "internet" and "abatis", is a per ...

Basic Additions and Deletions Check (CRUD) 01: Paging & Optimistic Lock & Default Insert Basic Additions and Deletions Check (CRUD)01 Base Additions and Deletions Check (CRUD)02 Basic Additions and Deletions Check (CRUD)03 Preface Tip 1: Indirect hesitation, persistent mixing and waiting to die!!! Not desirable or not Tip 2: ...