MySQL

To modify The root local login passwordModify the root default password (method one)1. After starting MySQL systemctl start Mysqld.service2. Modify the MySQL configuration file vi/etc/my.cnfFind [mysqld]Skip-grant-tablesSkip-networking3. Restart

Install MySQL with Yum under Linux, and start, log in, and remotely access the MySQL database. 1. Yum install MySQL1. Check that there are no installation packages:Yum List mysql*#移除已经安装的mysqlYum remove MySQL mysql-server mysql-libs compat-mysql51Rm-

1.WITH ROLLUP: Statistical data is performed on a group basis.Example: First grouping on the name field and then counting on a group basisMysql>SELECT Name,SUM(Singin) AsSingin_count from Employee_tbl GROUP by name with ROLLUP;+--------+-------------

14th Chapter-Using subqueriesUsing subqueries This chapter describes what subqueries are and how they are used.14.1 Sub-queryVersion requires MySQL 4.1 to introduce support for subqueries, so to use the SQL described in this chapter, you must use

Requirement: After using BULK INSERT, the ID of each record after insert is requiredNote: The Mybatis3.3.1 version later supports BULK INSERT after returning the primary key IDExample:Domin.java: Public classuser{Private intD; PrivateString name;

Sometimes MySQL master-slave synchronization is more serious when it requires manual synchronization.Let's talk about how to operate in the case of a lock table:The following is the brief process1. Lock the table for the main library firstFLUSH

I. OverviewUnlike other databases, MySQL can run different SQL model, SQL model defines the SQL syntax supported by the MySQL application, data validation, etc., which makes it easier to use MySQL in different environments.SQL model is commonly used

Integrity constraints for tablesConstraints are the same as the width of the data type, which are optional parametersRole: To ensure the integrity and consistency of dataMainly divided into:Not NULL identifies the field cannot be emptyDefault

a ViewA view is a virtual table (not a real one), which is essentially "getting a dynamic dataset from an SQL statement and naming it", which you can use as a table by simply using "name" to get a result set.Using views we can take out the temporary

1. Storage structureMyISAM: Each MyISAM is stored on disk as three files. The first file name begins with the name of the table, and the extension indicates the file type. frm file stores the table definition. The data file has an extension of. MYD (

Create a project file manually1. Under the specified directory, right-click to create the project folder.2. Use the GIT init command to turn the contents of this file into a file that can be versioned by git.3. Execute "npm init-y" command, create

Often have friends or colleagues ask, MySQL root password forgot, do not know how to do.In fact, the solution is very simple, the following is a detailed procedure.(1) Modify the configuration file my.cnf, add it under Configuration file

When we were hired to monitor MySQL performance, people wanted us to look at the MySQL configuration and give some suggestions for improvement. Many people were surprised after the fact because we suggested that they only change a few settings, even

#服务器端 TipsThe Vervice already exists!The current server installed#mysqld service does not startSolutionsRemoving the original MySQL serviceMysqld-remove MySQLOrSC Delete MySQLRe-registering the MySQL serviceMysqld–install mysql–defaults-file=

$servername = "localhost"; Server$username = "root"; User name$password = "root"; Password$dbname = "base"; Table name$params = Array (Pdo::mysql_attr_init_command = ' Set NAMES \ ' utf8\ ',//set character sets to ensure Chinese is not

Mysqldump is a good command for MySQL database backup, and it comes with MySQL.- D: Only the table structure is backed up, backup files are SQL statements, only statements that create tables are backed up, and the inserted data is not backed up.- t:

Common options:--all-databases,-A: Backing Up all databases--databases,-B: For backing up multiple databases, if there is no option, Mysqldump takes the first name parameter as the database name, followed by the table name. With this option,

What is a stored procedureSimply put, is a set of SQL statements, powerful, can implement some more complex logic functions, similar to the Java language method;PS: The stored procedure is a bit like a trigger, a set of SQL sets, but the stored

MySQL parameter optimizationMySQL parameter optimization for different sites, and their online volume, traffic, number of posts, network conditions, as well as the machine hardware configuration has a relationship, optimization can not be done at

Data type classification MySQL data types are divided into five categories, integer type, floating-point type, String type, date type, and other data types. Integer type: bit, bool, tiny int, small int, Mediun int, int, big int