Database Administrator

MySQL group then obtains the Top N pieces of data sorted by certain fields in each group, and mysqltopn MySQL group then obtains the Top N pieces of data sorted by certain fields in each group. Create a table CREATE TABLE `t` ( `a` int(11) DEFAULT

Use a timer to call the mysql stored procedure.1. Use a cursor to create a stored procedure SQL creation: create PROCEDURE daily_max_avg_online()BEGINdeclare max_online int;declare avg_online int;declare time TIMESTAMP;declare cur cursor for select

You cannot recover data with mysqlbinlog. Today, a new project was deployed locally, and the tables in another database were accidentally deleted. At that time, I did not find any hard disk recovery tools, I had to find another method. Fortunately,

MySQL root User forgot password solution (security mode, password modification methods), mysqlroot 1. Disable running MySQL2. Run the following command to start the Security Mode of MySQL: mysqld --skip-grant-tables Or mysqld-nd --skip-grant-tables

Summary of several balancing trees and summary of several balancing trees1. Introduction to 2-3-4 trees2-3-4 is a multiway tree. Each node has a maximum of four subnodes and three data items, the tree 2-3-4 can be regarded as the B tree with the

ORA-03249: automatic segment space management of the tablespace size should have at least 5 blocks, ora-03249 space size Create a tablespace for a test and report an error. SQL> select * from v $ version;BANNER ---------------------------------------

SQL single-user lock table unlock, SQL unlock USE master;GO DECLARE @ SQL VARCHAR (MAX ); SET @ SQL ='' SELECT @ SQL = @ SQL + '; KILL' + RTRIM (SPID) FROM sysprocesses WHERE dbid = DB_ID ('wms. MDF '); EXEC (@ SQL ); GO Alter database [WMS.

Work Summary: mysql uses strings as query conditions, mysql query Conditions Preface: I encountered a problem during mysql query today. The scenario is like this. Assume that one of my tables has a field scode (indicating the product number ), then

Alex's Hadoop rookie Tutorial: 8th Sqoop1 import Hbase and Hive, hadoopsqoop1 Continue writing. In fact, importing and exporting hdfs from mysql is useless for actual project development, but that can be used for getting started. Today we are

Transactions and stored procedures-the patron saint of data unification and the patron saint of Stored Procedures As the system grows and the amount of data increases, many operations on many tables in the database are required to implement a

Gp_gather_object_size script, zerosizeobject Because the database object (table) is too large and the business is busy, during the process of collecting statistics object size information, objects are often deleted and modified, resulting in the

Kettle tool User Guide, kettle tool use You can directly use kettle.zip to run Spoon. bat.   Ii. Conversion example: Data Conversion between databases A) create a new conversion db to db. ktl B) Create a database connection I. Click the main object

Oracle 11g installation causes the database to fail to automatically collect statistics, oracle11g Recently, it was found that some 11 GB databases could not automatically collect statistics. Some View query results are as follows: SQL> select

[Practice] The sphsf-index merging script is used to implement the sphsf-index. Mkdir/usr/local/sphscripts/scripts ---- 0. Create all primary indexes #! /Bin/bash # ocpyang@126.com # main_index_update.sh/usr/local/sphinx/bin/indexer src2-c/usr/local/

The SQL view obtains one field based on the where condition. First, we will introduce the usage of Case... When... Then... End: CASEJiXiaoFind_RowID WHEN '1' THENJiXiao_Money1WHEN '2' THEN JiXiao_Money2WHEN '3' THEN JiXiao_Money3WHEN '4' THEN

[Practice] sphinx starts to close the management script and sphinx script #! /Bin/sh #/usr/local/sphinx/bin/# ocpyang@126.comsphinx _ pidfile =/usr/local/sphfile/var/log/searchd. pidif [-e "$ {sphinx_pidfile}"]; thensphinx_active = 1 # runing # echo

Brief description and example of MySQL replication, and Brief Description Example of mysql Master-slave replication is widely used in MySQL. It is mainly used to synchronize data on one server to multiple slave servers. It can be used for load

Generate multiple ADDM reports and oracleaddm reports in OracleI have written an article in Oracle to generate AWR reports in batches. We used to monitor AWR reports every day to eliminate performance risks in a timely manner. Now there is another

Object-oriented features In UML, I learned about object-oriented, so I have a preliminary understanding of object-oriented, which lays a good foundation for a more convenient understanding of object-oriented in the future. Abstract, encapsulation,

Summary of common mysql commands and common mysql commands I. Database-level operations 1. log on to mysql The common format is mysql-u user_name-p. Press enter and enter the password and press enter again. 2. view all existing databases Show