Modify table structure

Learning objectives: 1. Modify field related information 2. Modify constraints 3. Modify other options 4. Modify table name Learning content: Create table Syntax: create table if not exists table name( Field type constraints, ... [constraint information]# last line information without comma )engine=InnoDB[MyIASM] default charset=utf8; For examp ...

Posted by aiikcmo on Tue, 10 May 2022 23:39:45 +0300

1.3 MySQL multi table & foreign key & database design, multi table relationship, multi table query, internal and external connection query, sub query, three paradigms and anti three paradigms

catalogue 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 solutions 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 ...

Posted by roy on Tue, 10 May 2022 18:19:19 +0300

MyBatis learning notes (including SSM integration and reverse engineering)

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 ...

Posted by kyme on Tue, 10 May 2022 16:23:56 +0300

Data warehouse 001 - full backup of time zipper

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. use test //Create business table user_data and give the initial business data. create table user_data( userid int, ustate varchar(4) ); insert into user_da ...

Posted by Mark.P.W on Tue, 10 May 2022 06:57:38 +0300

Zabbix 5.0.0beta1 experience 1- MySQL monitoring

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

My JDBC learning path

JDBC 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 database Connect before mysql8 Database driver name: com mysql. jdbc. Driver url connection: ...

Posted by mrhinman on Mon, 09 May 2022 06:28:50 +0300

MySQL index as I understand it

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

Sqlzoom exercises and answers

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

Conditional query of mysql

Advanced 2: condition query Take the following database as an example to write a conditional query case Syntax: select Query list from Table name where Screening conditions; Classification: 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

Technology sharing | common causes of MySQL startup failure

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