Database Administrator

About the three date types in MySQL After two insert date types recently, the value is 0000-00-00 00:00:00, so I checked the official documentation and found the reason. In Mysql, we often use three data types to store dates: Date, Datetime, and

Environment configuration of MyBatis I wanted to learn about mybatis a long time ago. It is said that many companies use this framework. In the past, I used DBCP, Which is outdated. Hibernate felt too big. Now I want to learn this neutral framework.

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

[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

Index statistics collected bug, collectedThe SQL Execution engine obtains the data that generates the optimal execution plan from the dictionary tables and views of related systems, such as pg_stats and pg_class. If the data in the dictionary view

Start the database and start the oracle database Database STARTUP (STARTUP) Three steps are required to start a database: 1. Create an Oracle instance (not in the installation phase) 2. Database Installation By instance (installation phase) 3. Open

Delete duplicate dataDelete from cbe_subscriberWhere rowid! = (Select max (rowid)From cbe_subscriber BWhere a. SUBSCRIBERKEY = B. SUBSCRIBERKEYAnd a. APPLYTIME = B. APPLYTIME );ORACLE deletes duplicate data I have already tried it. [Line ].Delete

Imp import and exp export, Imp Import and Export exp Import as needed (log files must be added ):C: \ Users \ Administrator> exp scott/scott @ orcl11g file = 'd:/temp/1. dmp 'Log = 'd:/temp/log. Log' Note: The data of the current user is exported.

Rman (I), rman (CHANGE command to CHANGE the backup and copy status1. change backupset 100 unavailable The CATALOG command is used to add backup fragments and copies to the RMAN database.1. Add the data file copy information to the RMAN

Oracle cannot import the empty table solution. oracle Solution Oracle cannot import empty tables C: \ Users \ Administrator> sqlplus/as sysdba SQL * Plus: Release 11.2.0.1.0 Production on Sunday August 17 19:24:29 2014 Copyright (c) 1982,201 0,

Collect oracle statistics and oracle statistics Manual refreshing of ORACLE statisticsSelect count (1) from LOG_TRX_DETAIL;Select * from user_tab_statistics where table_name = 'Log _ TRX_DETAIL ';Exec dbms_stats.gather_table_stats ('ardb', 'acct _

Mysql automatic backup and Mysql backupMysql automatic backup batch processing command: Set "Ymd = % date :~, 4% % date :~ 5, 2% % date :~ 8, 2%" Set "hMs = % time :~, 2% % time :~ 3,2% % time :~ 6, 2%" Mysqldump-uroot -- password = password weixin>

Oracle job, oracleEnable the specified job:BEGINDbms_auto_task_admin.enable (Client_name => 'SQL tuning advisor ',Peration => NULL,Window_name => 'Monday _ window ');END;/How to Create a job in oracle Replace the following stored procedure name with

Kettle javascript step error handling, kettlejavascript Javascript Step Error Handling   If you are familiar with the incorrect features of kettle conversion, you may want to know how to use it in javascript steps. The steps and user interfaces that

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

The location where SQL Server obtains the last character. CHARINDEX ('characters', reverse (field name )) This means to reverse the field, that is, to retrieve the last position of a character from the back to the front. Obtain the final position

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

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.