You can’t specify target in MySQL The error of table for update in FROM clause means that you cannot select some values in the same table first, and then update this table (in the same statement)
Category: Mysql
MySQL is a relational database management system, developed by the Swedish company MySQL AB, and currently belongs to an Oracle company. MySQL is the most popular relational database management system. In terms of web applications, MySQL is one of the best RDBMS (Relational Database Management System) application software.
MySQL backup file. XB database backup restore
Today an old friend told me that his mysql backup file suffix .xb could not be restored, or it was restored with only tables without data, so I decided to try I did a backup and restore, and I sear
MySQL supported data type
Data types supported by mysql Integer ”’ Type tinyint: 1 byte, value range -128~127, default length 4 smallint: 2 bytes, value range -32768 ~ 32767, default length 6 mediumint: 3 bytes int: 4 byte
MySQL data type
Data types are the basic rules that define what data can be stored in a column and how the data is stored
When designing a table, you should pay special attention to the data type used. Using the
MySQL master from mount
1. Modify the my.cnf file
vim /etc/my.cnf 1.1 Main Library< /p> #The current mysql service number is 1, which is the first mysql server
server-id=1
#Binary log file
log-bin=mysql-bin
1
Day41 – numeric type, integrity constraint
day41 Numeric type Integer type
mysql> create table t1(id tinyint); # The default is signed, that is, there is a sign before the number Unsigned setting mysql> create table t1(id tinyint uns
MySQL Backup – Back up all databases in turn using mysqldump
In some scenarios, the databases need to be backed up separately, and in some scenarios, all the databases need to be backed up together. Hereby we organize this backup script
#! /bin/bash
#
DDL operation table structure
DDL operation table structure: CRUD One, C (create) create 1, create table create table table name(
Column name 1 data type 1,
Column name 2 data type 2,
Column name 3 data type 3,
126 Mysql Storage Engine Overview
Table of Contents
Data in MySQL is stored in files (or memory) using various techniques. Each of these technologies uses different storage mechanisms, indexing techniques, locking levels, and
133 mysql view, transaction, index (very important)
Contents
# Data dependency: single table emp# Syntax# Create view mysql>: create view view name [( Aliases)] as select statement; eg>: create view v1 as select dep, max(salary) from emp group