MySQL multi table & foreign key & database design
1.1 multi table description
1.2 disadvantages of single meter
1.2.1 data preparation
1.2.2 single table problems
1.3.1 two tables are designed
Table 1.3.2 relationship analysis
1.3.3 problems in multi meter design
1.4 foreign key constraints
1.4.1 what ...
1. Introduction to mybatis
1.1 what is MyBatis?
MyBatis official website
MyBatis is an excellent persistence layer framework that supports common SQL queries, stored procedures and advanced mapping. MyBatis eliminates almost all the manual setting of JDBC code and parameters and the retrieval of result sets. MyBatis uses simple XML or ann ...
Demo in mysql
Full backup of zipper during mysql demonstration:
1, Demonstrate the first and second full backups.
1. First, there is the business system table.
//Enter the test database.
//Create business table user_data and give the initial business data.
create table user_data(
insert into user_da ...
Posted by Mark.P.W on Tue, 10 May 2022 06:57:38 +0300
It has been several months since the last article was published. Recently, there are many things to resume work, which has been delayed for some time. Look back at zabbix5 The 0beta 1 version has been released! The functions of the new version are described below. 5.0 has not been officially released at present. Do not use it in production envi ...
Posted by waldo on Tue, 10 May 2022 02:30:16 +0300
What is JDBC
JDBC (Java database connectivity) is a Java API used to execute SQL statements. It provides unified access to a variety of relational databases. It is composed of a group of classes and interfaces written in Java language
Connect before mysql8
Database driver name: com mysql. jdbc. Driver
url connection: ...
Posted by mrhinman on Mon, 09 May 2022 06:28:50 +0300
Hello, nice to meet you.
Starting from September, I decided to launch the goal of "weekly blog": publish at least one blog every week, which can be a variety of source code analysis and study, or a problem encountered in recording work.
After a period of aimless study, I found that it didn't seem to be very useful. I forgot what I had ...
Posted by kid_drew on Mon, 09 May 2022 00:21:49 +0300
0 SELECT basics
Displays the population of Germany
SELECT population FROM world
WHERE name = 'Germany '
A country with an area of more than 5000000 square kilometers displays its name and per capita GDP for each country
SELECT name, GDP/population FROM world
WHERE area > 5000000
Displays the country name and population of &quo ...
Posted by runawaykinms on Sun, 08 May 2022 22:06:06 +0300
Advanced 2: condition query
Take the following database as an example to write a conditional query case
1, Filter by conditional expression
Simple conditional operator:> < = != <> >= <=
2, Filter by logical expression ...
Posted by hammerslane on Sun, 08 May 2022 13:49:34 +0300
Author: Yao yuan
Focus on Oracle and MySQL databases for many years, Oracle 10G and 12C OCM, MySQL 5.6, 5.7, 8.0 OCP. Now Dingjia technology serves as a technical consultant to provide database training and technical support services for colleagues and customers.
Source of this article: original contribution * produced by aikesheng o ...
Posted by squalls_dreams on Sun, 08 May 2022 03:53:20 +0300
029 SQL basic query and data update
– workbench: Software
– query data: select //Query the name of fruit with a price of 10.2 yuan from the fruits table
select f_name(,f_price Better look) from fruits where f_price=10.2;
– query with in keyword: discrete value //Query s from the fruits table_ Records with IDS 101 an ...
Posted by spamyboy on Sat, 07 May 2022 23:01:58 +0300