Database Administrator

Temporary table VS table variables: suitable for use (1) For a long time, there has been a lot of debate over the advantages and disadvantages of temporary tables and table variables. Some friends in the Technical Group even think that table

Use the GROUP_CONCAT function of MySQL to implement aggregation multiplication.The MySQL aggregate function provides addition, average, minimum, and maximum, but not multiplication. Here we use the existing MYSQL GROUP_CONCAT function to implement

How can I remotely back up a database to a local database? How to remotely back up a database to a local database -- 1. Enable xp_mongoshelluse masterEXEC sp_configure 'show advanced options', 1 reconfigure with overrideexec sp_configure 'xp _

[SQL] queries the records used by a field in the database for a certain period of time. Sometimes we often need to use some tables or execute a stored procedure. Sort out the SQL queries executed by the database in a certain period of time. You can

Thoughts on triggers and triggers After reading Zhou's blog, I saw an article about the trigger. When you recharge your account, you need to insert a record in the t_reCharge table and update the t_card table to ensure data consistency. we didn't

Failed to open the physical file mdf. Operating System Error 5: "5 (Access denied .) ", Mdf cannot be openedFailed to open the physical file mdf. Operating System Error 5: "5 (Access denied .) "Environment: SQL Server 2008 R2 problem: "The physical

SQL sending email, SQL SQL version: SQL Server 2008 R2 Reference resources: Http://blog.sqlauthority.com/2008/08/23/sql-server-2008-configure-database-mail-send-email-from-sql-database/ Http://msdn.microsoft.com/zh-tw/library/ms190307 (v =

What does RAC mean? RAC: Real Application Clusters1 CRS management command1. Start crs (both nodes need to be executed)/Etc/init. crs start2. query the current crs status./Opt/oracle/crs/bin/crs_stat-t3. Stop crs (both nodes need to be executed)/Etc/

Install mysql in yum or mysqllinuxyum on linux Mysql installation is nothing more than the following. yum installation is also a type of rpm installation, but this installation package does not need to be downloaded separately. It is relatively

MySQL Full Join implementation, mysqljoin MySQL Full Join is implemented because MySQL does not support full join. The following is an alternative method: left join + union (deduplication is allowed) + right joinselect * from A left join B on. id =

[MongoDB] set up a Mongo Master/slave database for synchronization in windows, mongodbmongo In the previous series of articles, we talked about the basic operations, advanced queries, and index usage of mongodb. This blog mainly describes how to

A swap bug in the AIX6.1/11.2.0.3 database, aix6.111.2.0.3Yesterday, I went to a customer in Nanjing to optimize the new business database. I checked alert. when a log is found in the past period of time, the following content is reported every

Oracle tablespace query and maintenance command Daquan II (undo tablespace), oracleundo-- Undo tablespace Summary-- View All tablespace namesSelect name from v $ tablespace;-- Create a new UNDO tablespace and set automatic expansion

Undo tablespace, undo tableUNDO tablespace data file Switching1. Create an UNDO tablespaceCreate undo tablespace undotbs datafile '/dev/vx/rdsk/vgora/lv_undo' SIZE 10 m autoextend on retention noguarantee;2. Change the tablespaceAlter system set

Automatic oracle maintenance and oracle MaintenanceCheck whether the ORACLE automatic maintenance task is disabledSQL> select t. client_name, t. status from dba_autotask_client t;CLIENT_NAME STATUS-----------------------------------------------------

Database cache and database cache mechanismRefresh database cacheExec dbms_stats.gather_table_stats ('pro', 'tbl _ request', cascade => true );Alter system flush shared_pool;What is the database cache mechanism? That is, how does the cache function

Oracle when row function date, oracle when row Date of use   Oracle internal use of digital storage date: century, year, month, day, hour, minute, second. The default date display format is DD-MON-RR. -- Only the last two digits of a year can

[MongoDB] The basic operation of Index in MongoDB, mongodboperation In the past four blogs, we attached importance to the index, including description and comparison with usage of index. now in this blog, we will mainly focus on the basic operation

[SQL] Introduction to triggers-Special stored procedures and SQL triggers A trigger is a special type of stored procedure that automatically takes effect when data in a specified table changes. The difference between a trigger and a common stored

Data Analysis System DIY1/3: Installation documentary of CentOS7 + MariaDB, diy1centos7 We plan to systematically learn data analysis through practice. The three tasks to be completed in the preliminary plan. 1. Use VMware to install 64-bit CentOS.