information 2.2 OS details-> OS Processes shows the currently active processSummary: What do you think of Spotlight on MySQL? No, you are the development, testing or operation, with it you will be more effective, to have a little advantage, encounter bottlenecks and pressure he will be real-time alarm, alarm level can be customized, the rest or rely on everyone to explore. Spotlight on Unix and Spotlight on My
Parsing mysql: unique query for single table distinct and multi-table groupby to remove duplicate records bitsCN.com single table: distinct
Unique query for multiple tables: group
When distinct queries multiple tables, left join is still valid and full join is invalid,
When using mysql, you sometimes need to query records with unique fields. Although
Mysql Regular Expression queries records that contain non-numbers and characters, mysql Regular Expression
For example, we have a school table with the county_name field. Now we want to query records whose county_name field contains characters other than a-w letters and numbers. How can we write SQL statements? See the following statement:
select * from info wher
MySQL recursively queries the child node and parent node bitsCN.com of the tree table
Introduction: MySQL 5.0.94, which is a later version (5.5, 6, and so on) does not support recursive queries. compared with SQL Server and oracle, it is difficult for mysql to traverse child
Mysql group queries by time period to count the number of members and the number of mysql members
1. Use the case when method (not recommended)-
The Code is as follows:
Copy code
SELECTCOUNT (DISTINCT user_id) user_count,CASEWHEN create_time> 1395046800 AND create_time WHEN create_time> 1395050400 AND create_time WHEN create_time> 1395054000
Analysis of the lock table mechanism when mysql queries an update (only MYISAM is introduced) in order to better optimize mysql in high concurrency, it is necessary to understand the lock table mechanism when mysql queries an update.
I. Overview
MYSQL basic operation-data constraints and associated queries, mysql basic constraints Association
I. MYSQL Constraints
1. Default Value constraints. When a field does not have a value inserted, mysql automatically assigns a default value to the field.The default field can b
Mysql queries are sorted by the specified order of a field, and mysql fields are sorted by the specified order.
When using Sphinx in the project, many people encounter the following problem: After using mysql + Sphinx to retrieve the relevant ID, how can I sort it in Mysql
MySQL procedure mysql master phpmysql Chinese Linux
MySQL more than 1 million data query to use what technology can make the search speed improved? And the memory consumption will be reduced?
Reply content:
The simplest way to optimize queries is to index.If you want to do a higher level of optimization will
One way to monitor running MySQL is to check the status of MySQL running.(1) QPS (query amount per second)QPS = Questions (or Queries)/secondsMySQL > Show global status Like "question%";(2) TPS (transaction volume per second)TPS = (com_commit + com_rollback)/secondsMySQL > Show global status Like "Com_commit";
MYSQL queries data today, yesterday, 7 days ago, 30 days, and this month, mysql days ago
Today:
SELECT * FROM table name WHERE TO_DAYS (time field name) = TO_DAYS (NOW ());
Yesterday:
SELECT * FROM table name WHERE TO_DAYS (NOW ()-TO_DAYS (time field name)
Seven days ago:
SELECT * FROM table name where DATE_SUB (CURDATE (), INTERVAL 7 DAY)
30 days:
SELE
MySQL queries all records of a field that are not repeated bitsCN.com. assume that there are now N records that indicate
Id author title
1 aaa AAA
2 bbb BBB
3 ccc
4 ddd
5 eee AAA
Now I want to query all records with no duplicate titles from these five records.
Select distinct title, author from book is not allowed because distinct can only act on one field
Ask how to write
Answer:
Select a. * f
/libmysqlclient.so.15 '100%[===============================================================>] 1,474,856 195K/s in 9.2s2015-09-08 10:14:10 (157 kb/s)-'/usr/lib/libmysqlclient.so.15 ' saved [1474856/1474856]Once the download is complete, execute the command again to see the effect.virtualusmallinone:~#/usr/lib/nagios/plugins/check_mysql-s/var/run/mysqld/mysqld.sock-p PZyAHooqzyuptime:253321 threads:16 questions:2688108 Slow queries:6 opens:2551 Flush ta
Note and execute shell commands for Mysql queries. mysql executes shell commands.
Mysql query notes
1. when querying mysql, you must add the database prefix before the table. Otherwise, the database is the current database by default (when multiple databases are queried, d
Analysis of an optimization method for mysql associated subqueries and optimization of mysql associated queries
This article describes an optimization method for mysql associated subqueries. We will share this with you for your reference. The details are as follows:
In many cases, the performance of subqueries implem
15. SQL statement set. in Linux, PHP queries mysql and sqlmysql.
I. Create a database in mysql
Mysql password, no by defaultIf you want to change the value, mysqladmin-uroot password root123Logon: [root @ localhost root] # mysql-uroot-proot1231. Create a book DatabaseMysql>
.tar.gzMysql_performance_monitor_templates-0.9.1.tar.gz2.Zabbix web-side import of MPM templatesTemplates required for Zabbix Web UI Import Monitoring ("Configuration", "Templates", "Import"):The specific template file uses the following:Template_FromDual.MySQL.ndb.xml # Monitor MySQL clusterTemplate_FromDual.MySQL.security.xmlTemplate_FromDual.MySQL.innodb.xml # monitoring InnoDB storage engine state varia
Replication Class Tools1. Pt-heartbeatFunction Introduction:Monitor MySQL replication latencyUsage Introduction:Pt-heartbeat [OPTION ...] [DSN]--update|--monitor|--check|--stopMeasure how much time is left behind the main MySQL or main PostgreSQL, and you can use this script to update the master or monitor replication,
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