Database Administrator

View login users:You can:Show user;Select sys_context ('userenv', 'session _ user') from dual;Select user from dual; View all login users must be DBA users:Select username from v $ session;DBA users such as sys and system View objects (tables) in

DRBD (Distributed Replocated Blocak Device) Distributed replication block DeviceIn Versions later than 2.6.33, DRBD is compiled into the kernel, so DRBD works in the kernel. Let's take a look at the workflow of DRBD: 650) this. width = 650; "> When

For Oracle's learning and discussion, I will proceed directly below, and I will not discuss the history of Oracle, because the Oracle official team has a better explanation, here is a refinement of my knowledge about Oracle. For more information

The problem is that I want to obtain two adjacent rows with a row of records in a table and want to obtain them through union, so I write: Select id, title from subjects where id> # some_id # order by id limit 1 Union Select id, title from

Condition branch statement•IF statement:-IF-THEN-END IF-IF-THEN-ELSE-END IF-IF-THEN-ELSIF-END IF-Case statement:• Cyclic statements-LoopSyntax: IF condition THEN Statements; [ELSIF condition THEN statements;] [ELSE statements;] End if;

If you encounter a large amount of AWR data in your daily work, you can clear it as follows:SQL> select distinct dbid, db_name, instance_name from wrm $ _ database_instance;DBID DB_NAME INSTANCE_NAME-----------------------------------2691876695 MYDB

When the LV status is abnormal during the database management process and the LV cannot be used again, what are the two LV statuses in AIX? If open is required to access fs, that is, to create a file system and mount the file system lv state, it is

Rownum and rowid are all pseudo columns. However, rownum is a logical number and its value always starts from 1. The rounum of each row is not fixed. The rowid is a "physical" number. If the database file is not moved, the rowid of each row is

I received a call from my colleague at home, saying that the database could not be connected. The following error was reported during connection: ORA-12516: TNS: The Listener cannot find the available handler that meets the protocol stack

In Oracle 9i/10g, if the database instance does not have the scott mode, you can manually create it as follows: Log on to the database Create scott user Assign permissions to scott users Log On with scott user 1. Execute the following SQL

The Oracle paging query is generally implemented as follows:Select * from (Select a. *, rownum r from (Your own SQL) A where rownum ) Where r>? If this SQL statement is sorted by a field containing repeated values Duplicate records will be found on

I. cursor Let's talk about the concept of cursor first. From the perspective of the Oracle database administrator, cursors are collectively referred to as executable objects stored in the database cache. An SQL statement is stored in the database

Oracle user status Currently, databases, especially Oracle databases, are used in many industries. However, many enterprises seldom invest in database management and maintenance. The actual problems are self-evident: 1. DBAs have worked very hard to

Install MySQL in Ubuntu To install MySQL, run the following command at a terminal prompt: Sudo apt-get install mysql-server mysql-client # midway will let you enter a root user password sudo apt-get install php5-mysql # installation php5-mysql is to

Test Oracle 11g fixed execution plan-Baseline 1. Select SQL _id SQL>Pagesize 300 SQL>Set linesize 300 SQL>Set autotrace on SQL>Var name varchar2 (10 ); SQL>Exec: name:='It'; Select department_name From hr. departments dept Where

Configure Oracle listener in Linux to remotely connect to the database Server: Export LANG = "zh_US" 1. Add a listener: terminal running:$ ORACLE_HOME/bin/netca(In the graphic interface environment), add a listener as prompted.2. added services

Key Generator primary Key Generator the element is used to set the identifier generator. Hibernate provides the identifier Generator interface org. hibernate. id. IdentifierGenerator, and provides multiple built-in implementations. For example, org.

MongoDB provides an interesting "multikey" feature that can automatically index arrays of an object's values.However, the results with Multikeys are not surprising at first.Let's take a look at the test example:Save multiple test statements to a

Ubuntu version: 12.04 LTS MySQL version: MySQL Community Server 5.5.25 Installation Directory:/usr/local/development/mysql-5.5.25 1. Open the websiteHttp://www.mysql.com/downloads/mysql/To download the MySQL version (this article selects the 64-bit

1. Introduction MySQL supports unidirectional and asynchronous replication. One server acts as the master server during the replication process, and one or more other servers act as slave servers. The master server writes updates to the binary log