mysql pivot table

Label:Modify Table Name ALTER table name RENAME to new table name; A single SQL statement can only modify one table Show tables; 1. SELECT CONCAT ( ', table_name, ' RENAME to Db_ ' , 4 ), '; ' ) from information_schema. TABLES WHERE 'ct%'; Bulk copy to notepa

table, you can pass: Altertable TableName Engine=innodb;Shrink the unused space.b) The use of Turncate table for Innodb-plugin InnoDB also shrinks the space.c) For tables that use stand-alone table spaces, no matter how they are deleted, the fragmentation of the tablespace does not affect performance too much and there is a chance to process it.Disadvantages:Sin

require highly available scenarios. It is said that there are many similar telecommunications enterprises have been fooled on the MySQL Cluster, hehe.Limited resources, the opportunity to re-test and update the blog post, O (∩_∩) o haha ~Add: Try to make a node ndbd and SQL process forcibly killed, memory table total size about 6414MB, disk table total size abou

MySQL table name and other case sensitive issues: http://blog.csdn.net/postnull/article/details/72455768;1 MySQL under Linux database name, table name, column name, alias casing rules are like this: 2 1 , database name and table name are strictly case-sensitive; 3 2 , the al

How to create an associated mysql table-PHP, which is usually used for single-table operations, has never made any progress. recently, after reading a few open-source articles, it has become more dynamic. Books and videos that have been read all the time are operations on a single table. Now we need to implement a func

MYSQL Tutorial: MYSQL data table random number removal has previously been discussed in the group, it is more interesting. mysql syntax is really fun. they all wanted to use PHP to implement random queries, but retrieving multiple entries seemed to require more than two queries. after reading the manual, find the follo

MySQL inserts the data queried in Table a into Table B if Table B has 1codeclasssqlcodeclasssqlcodeclasssqlinsertintobselect * froma; codecodecode if Table B does not have 1 partition MySQL inserts the data queried in

Summary:how to drop MySQL database tables and recreate them if you have foreign keyrelationships between the T Ables.This is pretty obscure, but I thought I ' d post it It's I wouldn ' t forget how to do this ... if you ever has a situatio n When using MySQL where: You ' re just starting to use a database table The

MySQL transaction table is an important concept of MySQL database. The following describes the differences between MySQL transaction table and non-transaction table in detail. We hope you can have a better understanding of

Mysql alter table command to modify the table structure instance details, altertable The mysql alter table statement can modify the basic structure of a table, such as adding a field, deleting a field, adding a primary key, adding

Label:With the long-term use of MySQL, you can fix the table to optimize and reduce disk footprint when optimizing. Easy backup.REPAIR table ' table_name ' repair form REPAIR table is used to repair corrupted tables.OPTIMIZE table is used to reclaim unused database space, an

I have introduced how to update another table with one table. Now let's take A look at the SQL statement article about mysql update updating table B based on table A. I hope this article will help you. Recently, I encountered A requirement that both

Myisam table to innodb table to convert from InnoDB engine to MyISAM engine. after reading this article, you should know how to convert MyISAM engine to InnoDB engine (please make sure InnoDB is enabled, mySQL command line show engines command view ). Mysql> alter table bob

MySQL row-level lock, table-level lock, page-level lock details page-level: engine BDB. Table-level: engine MyISAM, which is interpreted as locking the entire table and reading at the same time. Row-level: engine INNODB, locking a single row of records At the table level, t

valueAVG (field): Gets the average in each groupMax (field): Get the maximum value in each groupMin (field): Gets the minimum value in each groupSUM (field): Get and in each group 7.3 Having condition: two-time conditional filteringDescriptionA. WHERE-to-field conditional filteringB. Having a condition filter on a running result,Combine grouping using 7.4 Order By field: sort fieldsDescriptionORDER by field [ASC Ascending | Desc Descending] 7.5LIMIT [$offset,] $length: Show N RecordsDescription

Tags: tab BLE ROM structure Select pre data table one1. Copy table structure and data to new table CREATE table new Table select * from old table 2. Only copy table structure to ne

With the long-term use of mysql, some problems may occur. In general, mysql tables cannot be accessed, and the tables can be repaired. During optimization, the disk space is reduced. Convenient backup. With the long-term use of mysql, some problems may occur. In general, mysql tables cannot be accessed, and the tables

Verify MySQL master-slave consistency (pt-table-checksumamp; amp; pt-table-sync) percona-toolkit-2.2.8-1.noarch.rpm has two tools to verify MySQL master-slave data consistency Installing tookkit requires some dependent packages Yum install perl-DBI perl-DBD-MySQL perl-I

The MySql stored procedure dynamically creates a table and inserts data to a recently created Project. The database uses MySql, which is not very skillful in MySql, but can be simply used, after all, simple SQL statements are still the same, but as the project goes deeper into complicated SQL statements,

The unique query for the single table uses: DISTINCT multiple table unique query with: GROUP BY distinct query multiple tables, the LEFT join is also valid, full connection is invalid, when using MySQL, There are times when you need to query for records that are not duplicated in a field, although MySQL provides