Database Administrator

I. Horizontal and vertical tablesHorizontal table: usually refers to the table we create in the database at ordinary times. It is a common table creation method.(Primary Key, Field 1, Field 2...) such as: time, customer ID, basic call fee, roaming

The mysql5.6 subquery is no longer a vase or a decoration. Mysql subqueries have always been known for poor performance. Therefore, the solution is to replace subqueries with table connections. In mysql, subqueries are only considered a function

PhpMyAdmin is installed by default and can only be connected to one MySql server. Its configuration information is stored in the phpMyAdmin configuration file. When we need to switch between multiple servers for login, it is very troublesome to

1. First install the following necessary rpm packages with the root user # Rpm-Uvh libaio-0.3.106-3.2.x86_64.rpm# Rpm-Uvh libaio-devel-0.3.106-3.2.x86_64.rpm 2. Supporting asynchronous I/O at the system levelUnlike setting asynchronous IO in RHEL3

For cainiao, I would like to explain [install mysql]. It is a general term to use the mysql database on linux, but it is unclear how mysql runs. In fact, mysql is divided into mysql server and mysql client. Therefore, these two [software packages]

OS Version: RHEL5.6-x86-64 DB version: Oracle 11.2.0.1 When I used dbca to create a database today, an error occurred in the progress bar of 61%, and an XML file parsing error occurred: [Thread-71] [17:59:31. 528 CST] [BasicStep.

An exception occurred when I performed a Database Export task as follows: An error occurred while importing data:IMP-00017: The following statement failed due to Oracle error 1659:"Create table" TB_XXXXXXXX "(" SERV_ID "NUMBER (9, 0) not null

This article describes how to install the OracleDatabase 11g Release 2 64bit database on the 64ora17 64bit system. Assume that you have installed the 64ora17 64bit operating system and the swap partition is 2 GB, linux security is disabled and the

#/Etc/init. d/mysqld startStart MySQLIf you use this command for the first time, your/var/lib/mysql database will be created. # Mysql-u rootYou do not need to enter a password for the first time.It is better to add a password to prevent intrusion.

In Oracle, after delete is used to delete data, the storage capacity of the database is not reduced, and after a table is deleted using delete, the query speed of this table is the same as before deletion, it will not change. Because oralce has an

Sometimes a long character column needs to be indexed, which will make the index larger and slower. One policy is to simulate hash indexes. But sometimes this is not good enough, then? Generally, you can index the first few characters instead of

Recently, we have used arcplan for reports. When we need to display data at different date granularities, it is easier to use SQL statements to directly query data from the database. It is highly reusable and recorded. Annual granularity: displays

When a customer updates data, the database content is deleted by mistake, because the database is master-slave, but not backup (backup is very important !) Fortunately, the bin-log is enabled, and the entire log record has to be taken back to the

1. instance recoveryThe system automatically recovers when the instance is restarted.Judgment basis: the scn of the data file is inconsistent with the control file.Steps:(1) use the online redo log to roll the data to the SCN that is consistent with

1. First, you must understand that the dmp file imported and exported from Oracle is executed using the cmd command, rather than SQL plus. You can also use PLSQLDev to import and export data. Note that the executable file export selects the

#/Bin/bash# MySQL Cluster configuration Scheme# Purpose host name IP# Management node ndb_mgmd 192.168.40.129# Data node 1 ndb1 192.168.40.131# Data node 2 ndb2 192.168.40.132# SQL Node 1 mysqld1 192.168.40.131# SQL Node 2 mysqld2 192.168.40.132#

1 set operation Definition: displays the results of Multiple SQL statements in a logical integrated operation. By default, set operations are sorted by the first column of the First query in ascending order, except for union all: Minus: Get

Fault symptom:ERROR: 12-09-20 16:15:03 get the maximum size ERROR: CallableStatementCallback; uncategorized SQLException for SQL [{call USP_SYS_CMSCODE (?, ?, ?, ?)}]; SQL state [72000]; error code [1552]; ORA-01552: non-system tablespace 'users'

1. A ora-14452 error occurred while deleting the user. SQL> drop user ggtransfer2 cascade; Drop user ggtransfer2 cascade * ERROR at line 1: ORA-00604: error occurred at recursive SQL level 1 ORA-14452: attempt to create, alter or drop an index on

1. Problem description: Open sqlplus and log on with the system role Switch to scott user and switch to sys D:/> sqlplus sys/admin @ orcl as sysdba Next, the following error occurs: "TNS: The Listener cannot distribute client connections" 2.