The only constraint field exception when executing the SQL statement Duplicate entry '33382-1-0' for key xxx

... Foreword: When doing the project, execute the SQL statement and report Duplicate entry '33382-1-0' for key xxx exception Later, it was discovered that it was the only constraint, so I went to Google Baidu, and later solved it and recorded it. 正文: The code snippet is like this: session...


PostgreSQL is ready to use: library, tablespace, role, SCHEMA

... 前 sudo su - postgres // Switch to postgres user 1. PostgreSQL will create a superuser role and a database by default during the installation phase, both of which are postgres. a, modify the password of the PostgreSQL database default user postgres Sudo passwd -d postgres //delete the...


Mybatis passes parameters from the mapper interface to the XML summary

... (1) interface to pass a variable to the xml interface selectByPrimaryKey(String id); Corresponding xml <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.String" > Select * From table_name Where ID = #{id,jdbcType=VARCHAR} </select> (2) Pass...


Inversion Index (GIN) in PostgreSQL

... Index is a method of quickly querying data, which records the correspondence between one or more columns in the table and its physical location. Commonly used indexes are B-tree, Hash, etc. This article will introduce GIN, which is: reverse index. The inverted index (GIN) can handle...


Redis Lua programming and debugging tools use

... 前言 Redis to build the Lua interpreter from version 2.6.0. Lua, a lightweight scripting language, the fastest scripting language. The combination of the two will burst into a huge power. 简介 Redis Lua scripts can call native Redis commands, or custom control flows, logic operations,...


Redis lock mechanism handles high concurrency

... 文章文 Here we mainly use Redis's setnx command to handle high concurrency. setnx has two parameters. The first parameter represents the key. The second parameter represents the value. If the current key does not exist, the current key is inserted and the second parameter is used as the...


Removing the duplicate data in the mysql table

... , due to concurrency, causes the same amount of data in the database to be a few more, so you need to know the data. For example, the data of the duplicate name in the person table is removed (in practice, the same row data may be judged by multiple fields, which is determined by name...


Based on Rongyun API development customer service chat function

... The following content is my own development and summary experience, if there is similar, I am honored! The company is currently working on an app that involves chat with the customer service. 于是是什么到一个融云api chatting system. append (front end) chat is done by professional ios andorid...


View the memory usage of the LINUX process

... You can directly view the contents of %MEM after using the top command. You can choose to view by process or by user. If you want to view the oracle user's process memory usage, you can use the following command: (1)top top command is a commonly used performance analysis tool under...


HTML web page structure - static web page

... static html page is executed from beginning to end without a program is a pure html language, is not directly processed by the server to output to the browser to present to the viewer. The webpages of other suffixes are relatively dynamic webpage pages. The dynamic webpages are...