MySQL

First: The firewall used by CentOS 7 is: Firewall not iptablesTo view the ports that are already open: Here I've opened the MySQL port[Email protected] ~]# Firewall-cmd--list-ports3306/tcpOpen port: Prompt success indicates success[Email protected] ~

The character set is a set of symbols and encoding rules, whether in the Oracle database or in the MySQL database, there is a character set selection problem. For the database, the character set is more important, because the database stores most of

The importance of database backup, in the production environment, the security of data is very important, any loss of data can have serious consequences, database backup, timely recovery of important data. Causes of data loss: Program error

first determine to crawl the joke site, I was directly Baidu jokes to search the first site, the URL is http://www.jokeji.cn/, point to find web page construction in my opinion is still more complex, because still beginners, First of all, we must

Small comicsCome on, take a look at the little comic book to edify sentimentOK, here's the point. Suppose that you have a table ERP if you directly make the following commandAt this point all the MySQL related processes will stop until the drop is

Editing directives using the editorEditCreate a tableCREATE TABLE Table name (Field 1, type "width" constraint)= = in the same table, field names cannot be the same= = width and constraints optional= = Field name and type are requiredView TableShow

The problem is as follows:For example, the person table in the query SQL statement if the table name is lowercase, it will be reported that the people table does not exist.Because the table name of the MySQL database in the Linux environment is case-

1. If Else branch1 Create procedurePD_TESTIF2 (inchNumint, outStr varchar)2 begin 3 ifNum=1 Then4 Set Str='a';5ElseIf num=2 Then6 Set Str='two';7 End if;8 End;9 --calledTenCall PD_TESTIF2 (1,@str); One

Database Rights Management has always been a very troublesome thing, because the permissions are very decentralized, not easy to view, nor easy to modify the perfect. But MySQL's privilege management gives the impression of a bright front. Because

I. What is an index? Why index?Indexes are used to quickly find a row with a specific value in a column, and without using an index, MySQL must start reading the entire table from the first record until it finds the related rows, the larger the

Introduction to Stored ProceduresReprint: https://www.cnblogs.com/mark-chan/p/5384139.htmlSQL statements need to be compiled and executed, and stored procedures (Stored Procedure) are a set of SQL statements that are compiled in order to accomplish

ICP (Index condition pushdown) is an optimization of MySQL's use of index (level two index) tuples and sieve fields to extract data records from a table in the Where condition in the index. The idea of ICP is that the storage engine examines the

1. Start mariadbSystemctl Start mariadb2. Set Boot mariadbSystemctl Enable MARIADBFirst, change the user password, take root as an example1. Know the root password, need to modifyMethod A. Log into the database to modify # mysql-uroot-p/*

data Query Language DQLBasic QueryGrammatical formSELECT [All | distinct] field or expression list [FROM clause] [WHERE clause] [GROUP BY clause] [HAVING clause] [ORDER BY clause] [limit clause];Select AVG (degree), CNO from score where CNO like "3%"

MySQL Execution plan Optimizing queries with explain Explain output format Extended Explain output format Get execution plan information for a named connection Estimating Query Performance EXPLAIN Syntax

MySQL Master-slave replicationDeployment Environment:MySQL Master 192.168.40.21MySQL slave 192.168.40.22Ideas:When the data on the main MySQL operation or changes, the main MySQL binary log files (binary logs) will be changed, when the I/O thread

Before the solution, you have to explain why there is an error, emoji expression occupies 4 bytes, but MySQL database UTF-8 encoding can only store 3 bytes, it will cause storage not to go inHow to troubleshoot emoji storage issuesMySQL UTF8 encodes

1, Linux under the installation of MySQL is the default: distinguish the case of the table name, do not distinguish between the case of the column name;2, with the root account login, in the/ETC/MY.CNF [mysqld] After adding add

In the actual project development, because we do not know what is happening in the database when the actual query, database software is how to scan the table, how to use the index, so we can perceive onlyWhen the SQL statement runs, the query is

Regular Expressions are a powerful way to specify patterns for complex searches. MySQL adopts the Regular Expression of Henry Spencer, and its goal is to comply with POSIX 1003.2. SeeAppendix C: Thank you. MySQL adopts an extended version to support