MySQL

I. The role of affairsA transaction is a sequence of successive operations that will occur.Transaction security is to ensure that the results of a series of operations are kept in sync to ensure data integrity.When a transaction is turned on, the

The MySQL database has a concept of autocommit transactions, autocommit. The implication is that if autocommit is turned on, each statement is automatically committed after execution. That is, a statement is treated as a transaction.In the mysqldb

Interactive_timeout: The number of seconds that the server waits for activity before closing an interactive connection. The interactive client is defined as a client that uses the Client_interactive option in Mysql_real_connect (). See Wait_timeout

MySQL Operations database1. Create a databaseCREATE database name;2. Show created DatabaseSHOW DATABASES;3. Select the database you have createdUse database name;4. Deleting a databaseDROP database name;5. Database Storage EngineInnoDB: is a

1. Verify that the initial remote connection is allowedSince this virtual machine IP is 192.168.2.120, we doMysql-h 192.168.20.120-p 3306-u root-proot (Note:-proot,root refers to the password of the root account),Can get results connected not on.If

First, the index length and the degree of differentiation are contradictory,The index length is too short, then the sensitivity is very low, the index length is longer, the sensitivity is high, but the index is to occupy memory, so we need to find a

Friday received a small help to develop a friend, need in The MySQL test environment creates a stored procedure that automatically creates a user and asks for help writing. MySQL version 5.5.17OS version CentOS 6.4The contents of the stored

#!/bin/bashusername=roothostname=localhostpassword=rootmysql-u$username-h$hostname-p$password-e "Show Databases" Read-p "PLZ input a dbname:" dbnameread-p "PLZ input backupdir:" backupdirread-p "PLZ input backupname:" BackupName if [["$dbname" = = "

1, by the hour statistics statementSelectConcat (Date_format (gmt_create, "%y-%m-%d%k:00~"), Hour (gmt_create) +1, ": xx") as ' time ',COUNT (*) as NumFrom T_orderwhere gmt_create>= ' 2016-03-06 00:00:00 ' and gmt_createGroup by left (Gmt_create, 13)

I. INTRODUCTION OF TriggersTrigger (trigger), bind some code in advance for a table, and when this table data changes, the system will automatically call these bound code.Event Type: Insert, delete, updateTrigger time: befor, afterEvent object: Each

First, new dataInsert into view name [(field list)] VALUES (list of values);Note:1. Multiple table views cannot add data.2. A single table view has a base table all fields that cannot be empty or have no default values can add data.Ii. deletion of

By default, after MySQL is installed, there will be anonymous users, or you can call an empty user, enter MySQL and then go directly to MySQL.The anonymous user has certain permissions through show DATABASES; you can view the INFORMATION_SCHEMA

Select* from where a.batch_no = ' ss20170123181418' ;This is the original data:This is what it looks like after a row-to-column:SelectA.debt_type,sum( Case whenDebt_type='0' ThenAMOUNTEND)'Initial Debt',sum( Case whenDebt_type='1'

MySQL executes the INSERT and other statements to report the following error:1205 Lock wait timeout exceeded try restarting transactionThe solution is as follows:Method One: View the current thread, if there is a statement that is executing you,

Since the operation of the database from the database link to write, including the building, building tables, add and remove the Check field and constraints, delete the library, delete the table of data, the following is mainly my previous interview

Create a stored procedure, trigger, and a simple instance (image and text) using a cursor in navicat. 1. Create a tableFirst, create two tables (users table and number table). The specific design is as follows: 2. Stored ProcedureWrite a stored

Configure mysql in MAC ox and mysql in macox Download MySQL Installer: http://dev.mysql.com/downloads/mysql/Select the dmg package, download the package, double-click it, open the corresponding pkg package, and click Next until the installation is

PACK_KEYS and mysqlPACK_KEYS in mysql Original http://jackyrong.iteye.com/blog/2170222   One of the myisam engines in mysql is easy to ignore, called the compressed index PACK_KEYS, MyISAM uses prefix compression to reduce the index size. By default,

Enable phpmyadmin. The advanced function is not fully set. Some functions are not activated.     Q: How can I solve this problem if I enable phpmyadmin to display advanced functions that have not been fully set and some functions are not activated?

MySQL index and mysql Index Mysql indexes use B + tree. B + tree is a variant of the balanced binary tree, so the query speed is very fast. (B + tree: https://zh.wikipedia.org/zh-hans/ B %2B%E6%A0%91) Indexes mainly include clustered indexes and