MySQL

1. Innodb_lock_wait_timeoutMySQL can automatically monitor the deadlock caused by the row lock and handle the corresponding, but the deadlock caused by the table lock cannot be automatically monitored, so this parameter is mainly used to wait for a

Review:ACID: In the process of writing or updating data, the DBMS has four features for ensuring that transactions are correct and reliable: atomicity (indivisibility), consistency, isolation (independence), persistencea transaction : A complete

Assuming that the operating system is reinstalled, many local software may need to be re-installed, such as a database. However, assuming that we have some important software installed in the virtual machine, the database server can be backed up

MySQL simple operation one, view the database show DATABASES; for example: MariaDB [(None)]> show databases;+--------------------+| Database |+--------------------+| Information_schema | | MySQL | | Performance_schema | | Test |+--------------------+

1. Query the number of fields in a table:SELECT COUNT (*) from INFORMATION_SCHEMA. COLUMNSWHERE table_schema = ' database name 'and table_name = ' table name ';2. Query How many tables are in a database:SELECT COUNT (*) TABLES, table_schema from

mysql-Slow Query logtags (space delimited): MySQLTurn on slow query log慢查询是一种mysql提供的日志，记录所有执行时间超过某个时间界限的sql的语句。这个时间界限我们可以指定。在mysql中默认没有开启慢查询，即使开启了，只会记录执行的sql语句超过10秒的语句[Way One]Enter mysql:mysql-uroot-h127.0.0.1-proot# to view the parameters related

1. View the IP that the MySQL port allows access to.netstat-an| grep 3306If displayed as the following, only native access is allowed.TCP 0 0127.0. 0.1:3306 0.0. 0.0:* LISTEN2, modify

1. Data sheet operationThe data table is the most important thing to store the data, it exists in the library, there can be more than n tables in a library. Therefore, you must select a library to create a data table.1.1 Creating a data tableCREATE

1 Enter mysql-uroot-p in the command window first via cmd into MySQL2 Changing the encryption methodmysql> ALTERUSER‘root‘@‘localhost‘IDENTIFIED BY‘password‘PASSWORD EXPIRE NEVER;Query OK, 0 rowsaffected (0.10 sec)3 Changing your

On the Internet to find a national and provincial latitude and longitude of the JSON file, you can also use the last method, parse the JSON keyword, construct SQL statement, insert the database.The JSON file format is as follows:[ { "Name":

From the front-end inserted in Chinese, to the background MySQL view is a question mark.Can not be displayed in Chinese, the initial decision is the problem of coding.We useShow variables like ' character_set_% ';AndShow variables like ' collation_%

This document is to help develop and OPS to use MySQL database in accordance with the specification, improve the level of research and development writing SQL. Committed to providing a secure, stable, high-performance database environment. naming

1. Data manipulationData tables are used to store specific data, and once you have an understanding of the data table, you should know how the data table holds the data.1.1 Add record (insert data)Grammar:Insert into Table name (field list) VALUES

First OrderIn this paper, according to the 11th chapter of MySQL operation and control InnoDB Log management mechanism, this book focuses on the principle of log generation, format, working principle, brush disk mechanism. Space-constrained,

To know the size of each database, proceed as follows:1. Access to the INFORMATION_SCHEMA database (information on other databases)Use INFORMATION_SCHEMA;2, query the size of all data:Select Concat (Round (sum (data_length/1024/1024), 2), ' MB ') as

Python crawl room World City dataWith the rise of the internet era, technology is changing rapidly, mastering a new technology for career development has a profound significance, do the first demo, will be in the crawler and data analysis to

ClassificationThe installation development sequence is divided into: Web-based database Hierarchical database relational database Object-oriented database Mainstream: relational databaserelational databaseTransaction

Query cache:Cached data: k/v, which is a key-value pair;Key: The hash value of the query statement;Value: Query result of query statement;To determine whether the cache hits the standard:By comparing the hash value of the whole query statement, the

The following are the database error message prompts that appear for common installation plugins:Code:duplicate column name ' Allowrank 'Upgrade data Occasionally, it means that the table already exists. However, if it is installed, the following

PXC Introduction:The Galera product is a galera cluster way to improve the high availability clustering solution for MySQL. Galera cluster is a MySQL cluster with integrated Galera plugins. Galera replication is a MySQL data synchronization scheme