MySQL

1, MySQL has a lot of useful functions, good use of them can save a lot of time:Group_concat () the value to be taken is concatenated with commas, so you can use:select group_concat(distinct id) from tablename;The results are similar to:

MySQL includes support for triggers. A trigger is a database object associated with a table operation that invokes the execution of a trigger on a table when a specified event occurs on the table on which the trigger is located.Create a TriggerIn

1. The transaction has acid four characteristics.1. atomicity (automicity): All statements in a transaction should be done: either wholly or not;2. Consistency (consisitency): Let the data remain logically "reasonable", such as: When a commodity out

This document to learn the experimental environment, the content of experimental results are all in the computer room calibration, all correct.System environment: RHEL6 x86_64 SELinux and iptables disabledSoftware Download: http://Poptop. 

Check if MySQL Server is installed:Rpm-qa | grep MySQLRpm-qa | grep mariadbDelete method:RPM-E MySQL #普通删除模式Rpm-e--nodeps MySQL #强行删除模式, if you use the above command to delete, prompted to have other dependent files, then use this command can be

The previous understanding of InnoDB on the occurrence of lock waiting, will be based on the configuration of the parameters Innodb_lock_wait_timeout, determine whether to do a timeout operation, this document describes in the presence of lock

Float numeric types are used to represent single-precision floating-point numbers, whereas double numeric types are used to represent double-precision floating-point numbers, float and double are floating-point, and decimal is fixed-point;MySQL

Install using the following command:RPM-IVH mysql-server-5.6.19-1.linux_glibc2.5.x86_64.rpmThe error prompts are as follows:  Preparing ... ########################################### [100%] File/usr/share/mysql/charsets/readme from install of

send a basic, about MySQL data Export Import article, the purpose is two:1. Memo2. For developers to testToolsMysql/source ImportMysqldump ExportApplication ExamplesExport Export a full library backup to a local

Linux default off MySQL remote connection, edit/etc/mysql/my.cnf file,Change the inside bind-address = 127.0.0.1 to bind-address = 0.0.0.0,Then restart the MySQL service, enter the command:/etc/init.d/mysql restart,Next, create and assign users and

B-TreeB-Tree, here is balance (balanced meaning), B-Tree is a multi-path self-balancing search tree It resembles a normal balanced binary tree, the difference is that the B-tree allows each node to have more child nodes. is a simplified map of

Apache+php+mysql Separating and building lampApache and MySQL installations are not describedWhen layered 1. Apache Configuration file Modification 1), enable the relevant module httpdAfter Apache HTTPD 2.4 has a module specifically for the

Download down the package, after the decompression will have an installation documentation, usually called a readme or install, look at the installation process, there must be make the source package. Another is through the name, the specification

Install R and MySQL is no longer said, there are many online tutorials can be found. The following goes directly to the ODBC installation process.1. Download and install Mysql-connector-odbc-5.x.x-win32.msi:

Soft text link: http://blog.csdn.net/likendsl/article/details/7530979http://blog.csdn.net/luwei42768/article/details/48732611Show variables like ' character%View SettingsSet character_set_client = UTF8MB4;  Set character_set_connection =

recently, as requested by the team, the study collated the following MySQL-related optimizations, some of which are based on actual Java projects encountered in the context of experience. Welcome to the discussion ~The SQL language is a powerful and

Quickly deploy MySQL and one machine and multiple instances to deploy mysql instances MySQL has three versions: binary, source code package, and RPM. The following describes how to install a binary package. :

Use SQL statements in MySQL to rename fields. In MySQL, how does one use an SQL statement to rename a table field? We will use the alter table SQL statement. Syntax for renaming a field: alter table change . Now we will try to rename the t_name

Plugin 'federated 'is disabled or 1067 error startup error and "service mysql unexpectedly stopped" solution, federated1067 MYSQL startup reports a 1067 error. In the system log "service mysql unexpectedly stopped", the Mysql Log is: "Plugin

Tips for MySQL Introduction Storage Engine MyISAM is the default storage engine of MySQL5.1 and earlier versions. MyISAM provides many features, including full-text indexing, compression, and spatial functions (GIS). However, MyISAM does not support