MySQL

The company upgraded the server configuration, the memory crunch problem solved, and thus thought of several simple ways to optimize MySQL. First, two things are clear, our business scenario is a common high concurrency Web service, the query speed

When using MySQL, you need to know the current database, such as the current database size, character set, user, and so on. Here's a summary of some commands for viewing database-related information1: View Show all databasesMysql> Show databases;+---

The content of this article: System variables User variables Local variables Starting Date: 2018-04-18 System variables: System variables are variables that the system has already defined in advance.

#外键 table linked to table column name MUL foreign key referential integrity cannot add a field that does not have another tableCREATE TABLE Study_record (ID int auto_increment PRIMARY key,Day int is not NULL,Status char (+) NOT NULL,stu_id int NOT

Previously wrote a MySQL installation under Windows (click here), Linux used less, recently switched to the Linux server, the release of MySQL installation and Windows differ, only to record the compression package installation, RPM package similar1.

Cascade Action 1、cascade ：数据级联更新 当主表删除记录或者更改被参考字段的值时,从表会级联更新 2、restrict(默认) 当主表删除或者更新被参考字段的值时,如果从表中有相关联记录则不允许主表删除或更新,必须先删除从表中相关联记录 3、set null 当主表删除或者更新被参考字段值时,从表中相关联记录的外键字段值自动设置为NULL 4、no action(同restrict)

Already installed CENTOS7 and MySQL, the system is installed by default more than MARIADBTwo virtual machine IP192.168.0.103192.168.0.106Firewall Open portPermanent parameter means permanent

MySQL has a parameter log_bin_trust_function_creators, the official document of this parameter is introduced, the explanation is as follows:This variable applies if binary logging is enabled. It controls whether stored function creators can be

Objective:SQL injection want to learn, learn to pass. You have to understand the underlying SQLStatement. I'll get a quick haircut here.Body:Set up the environment suggestion Phpsduy Fast ConstructionSELECT * from KasiSelect field name from table

First, using the command line mode into MySQL will see the first prompt;View version Information#1使用命令行模式进入mysql会看到最开始的提示符Your MySQL Connection ID is 3Server version:5.1.69 Source DistributionSecond, the command line using status can be

Data Type Basic Introduction Numeric type整形类型：tinyint,int,bigint浮点类型：float,double String typechar系列：char varchartext系列：textblob系列：blob枚举类型：ENUM集合类型：SET Time Date Typedate time datetime timestamp year tinyint and int plastic testingmysql>

because sometimes there is a demand, need to open the Cloud database network address, but there are individual cloud operators do not provide this operation, after a few brainstorming, think of Nginx on another--with-stream module can map the

1, add foreign key while creating table1 CREATE TABLE Users (2Useridintprimary Key auto_increment,3Username varchar ( -) notNULL,4Password varchar ( -) notNULL5) Auto_increment =1001;6 7 8 CREATE TABLE Userright (9Idintprimary Key

1. What is the index of the structure used by MySQL?1). The MyISAM engine uses B+tree as the index structure, and the data domain of the leaf node holds the address of the record. Therefore, the algorithm of index retrieval in MyISAM is to search

RelationshipThe relationship between entities and entities is reflected in the design of the final database table. Divide the relationship into three categories: one-to-one, two-to-many (many-to-a) and many-to-many.All relationships refer to the

Wildcard characters in a selectAsterisks * can be used to select represent all the attributes in a clause.Mysql>SelectInstructor.* fromInstructor, teacheswhereInstructor.id = teaches.id;+-------+------------+------------+----------+|ID| name |

1. Change the passwordWithout knowing the original password: the process of shutting down MySQLEnter "Mysqld_safe--skip-grant-tables &" command to enter MySQL Safe mode without password.Then you can use a blank password like mysql-u rootshow

Controller:Private ReadOnlyVipviewmodel _model =NewVipviewmodel (); Public Static stringMSG;//Get:systemmanage/renzheng[HttpGet] PublicActionResult Index (intpage =1) { #regionData is populated to the custom modelvardb

I. Get the current system time and date and format the output:Import Java.util.date;import Java.text.simpledateformat;public class Nowstring {public static void Main (string[] args) { SimpleDateFormat df = new SimpleDateFormat

The company upgraded the server configuration, the memory crunch problem solved, and thus thought of several simple ways to optimize MySQL. First, two things are clear, our business scenario is a common high concurrency Web service, the query speed