因操作失误,在 Ubuntu下将Mysql卸载了,只得重新安装,折腾了半天,没有安装上去,执行 #sudo apt-get remove mysql-server #
因操作失误,在 Ubuntu下将Mysql卸载了,只得重新安装,折腾了半天,没有安装上去,执行
#sudo apt-get remove mysql-server
#sudo apt-get install mysql-server
然后再执行/usr/bin/mysqld_safe &提示以下错误
Can’t connect to local MySQL server through socket ‘/var/run/mysqld/mysqld.sock’ (2)
的确,在/var/run/mysqld下没有mysqld.sock文件, 然后还有一种错误是
/etc/init.d/mysql: WARNING: /etc/mysql/my.cnf cannot be read. See README.Debian.gz
在/etc/下也没有my.cnf文件。到这里没办法了,因为水平有限
最后终于找到一解决方法,执行
#sudo apt-get install mysql-server mysql-common
修改mysql登录密码
#sudo mysqladmin -u root -p password ‘newpassword’
其主要是mysql-common包,my.cnf之类的文件就是来自于mysql-common,,不过在安装前最好将其之前所有安装过的mysql数据数理干净,以名安装时出现其它之类的问题
又算是学了一招mysql的知识。

MySQL uses a GPL license. 1) The GPL license allows the free use, modification and distribution of MySQL, but the modified distribution must comply with GPL. 2) Commercial licenses can avoid public modifications and are suitable for commercial applications that require confidentiality.

The situations when choosing InnoDB instead of MyISAM include: 1) transaction support, 2) high concurrency environment, 3) high data consistency; conversely, the situation when choosing MyISAM includes: 1) mainly read operations, 2) no transaction support is required. InnoDB is suitable for applications that require high data consistency and transaction processing, such as e-commerce platforms, while MyISAM is suitable for read-intensive and transaction-free applications such as blog systems.

In MySQL, the function of foreign keys is to establish the relationship between tables and ensure the consistency and integrity of the data. Foreign keys maintain the effectiveness of data through reference integrity checks and cascading operations. Pay attention to performance optimization and avoid common errors when using them.

There are four main index types in MySQL: B-Tree index, hash index, full-text index and spatial index. 1.B-Tree index is suitable for range query, sorting and grouping, and is suitable for creation on the name column of the employees table. 2. Hash index is suitable for equivalent queries and is suitable for creation on the id column of the hash_table table of the MEMORY storage engine. 3. Full text index is used for text search, suitable for creation on the content column of the articles table. 4. Spatial index is used for geospatial query, suitable for creation on geom columns of locations table.

TocreateanindexinMySQL,usetheCREATEINDEXstatement.1)Forasinglecolumn,use"CREATEINDEXidx_lastnameONemployees(lastname);"2)Foracompositeindex,use"CREATEINDEXidx_nameONemployees(lastname,firstname);"3)Forauniqueindex,use"CREATEU

The main difference between MySQL and SQLite is the design concept and usage scenarios: 1. MySQL is suitable for large applications and enterprise-level solutions, supporting high performance and high concurrency; 2. SQLite is suitable for mobile applications and desktop software, lightweight and easy to embed.

Indexes in MySQL are an ordered structure of one or more columns in a database table, used to speed up data retrieval. 1) Indexes improve query speed by reducing the amount of scanned data. 2) B-Tree index uses a balanced tree structure, which is suitable for range query and sorting. 3) Use CREATEINDEX statements to create indexes, such as CREATEINDEXidx_customer_idONorders(customer_id). 4) Composite indexes can optimize multi-column queries, such as CREATEINDEXidx_customer_orderONorders(customer_id,order_date). 5) Use EXPLAIN to analyze query plans and avoid

Using transactions in MySQL ensures data consistency. 1) Start the transaction through STARTTRANSACTION, and then execute SQL operations and submit it with COMMIT or ROLLBACK. 2) Use SAVEPOINT to set a save point to allow partial rollback. 3) Performance optimization suggestions include shortening transaction time, avoiding large-scale queries and using isolation levels reasonably.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

VSCode Windows 64-bit Download
A free and powerful IDE editor launched by Microsoft

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment
