Database Administrator

Create test tableCreate table test1SELECT *FROM all_objectsWHERE 1 = 2;MATCHED and not matched clauses are optional ① Both clauses appear.Merge into test1USING all_objects BON (a. object_id = B. object_id)WHEN MATCHED THENUpdate set a. status = B.

This article demonstrates how to use Oracle ROLLUP grouping functions to experience the charm of Oracle functions in the field of statistical query. The ROLLUP grouping function can be understood as the simplified usage after the Group By grouping

1 oradebug Introduction Oradebug is mainly used by Oracle Support staff. Although it was very early, it is rarely recorded on the oracle official website. It is an SQL * plus command line tool. You can log on with sysdba permissions without special

Today I encountered a very serious problem... I installed a database of MySQL5.5.18 under CentOS6, but later I found that crontab was not installed.Yum install vixie-cron crontabsBut the following exception is reported:

MySQL string truncation functions: left (), right (), substring (), substring_index (). There are also mid () and substr (). Here, mid () and substr () are equivalent to substring () functions. substring () functions are very powerful and flexible. 1

Log on to Oracle as a sys user, SQL> grant sysdba to username; Grant sysdba to username *ERROR at line 1:ORA-01994: GRANT failed: password file missing or disabled First, change the value of the initialization parameter REMOTE_LOGIN_PASSWORDFILE to

According to the official Oracle documentation, the database character set cannot be changed after it is created. Therefore, it is important to consider which character set to use at the beginning of design and installation. For the database server,

After LNMP is set up, use PhpMyAdmin to import the database file, prompting that the file content is too large. Modified Upload_max_filesize = 30 M Post_max_size = 40 M Still useless. You can solve the problem as follows: Modify the config. inc.

1. Basic Steps for copying It takes only three steps to create a simple copy. Configure a server as the Master database, that is, the Master database. Configure another server as the slave database, that is, the slave database. Connect the

My system: Red Hat Enterprise Linux Server 6.0.My Oracle: 10g. 2.1 Installation Process in silent mode:1) confirm the disk size: u01 5G; swap 400 m;Du-sh/tmp/Df-h 2) install related dependency packages (query the official installation guide

An error occurred while connecting to the database using rman today.[Bkjia @ rhel55 ~] $ Rman target sys/Oracle @ orcl ORA-12514: TNS: listener does not currently know of service requested in connect descriptor[Bkjia @ rhel55 ~] $ Lsnrctl

(1) After the Oracle Database Console is started, 1) The database instance has no information. 2) The Listener is in the unavailable state. 3) the proxy connection status to the instance is unavailable. Problem analysis: the service has just started

Are you doing everything you can to optimize the performance of the SQL Server database? If your database contains a large number of tables, putting these table partitions into an independent file group may benefit you a lot. The Table Partitioning

Version: Tested on R12.0.6/R12.1.1 Note: Adjust the GUEST user password according to the specific environment. The default password is Oracle. The password of the GUEST user can be found in the $ CONTEXT_FILE file: View $ CONTEXT_FILE 51 52 GUEST 53

Environment MySQL 5.1 + command line tool Problem Garbled characters are displayed in the exported SQL statement of mysqldump. Solution Mysqldump-uroot -- default-character-set = utf8-p axt> kq. SQL Summary SQL garbled characters may

Problem description: If you accidentally delete the dbf file of the Oracle database, an error is prompted when you start or close the database. When startup starts the database, the following message is displayed: ORA-01157: unable to

Recurrence The problem that a colleague encountered when performing a data dump is simplified as follows: 1. Create a table Drop table if exists tb; Create table tb ( C timestamp not null default '2017-00-00 00:00:00' ) ENGINE = InnoDB default

System Environment: CentOS 6.3 X86_64 Redis Introduction Redis is essentially a Key/Value database, similar to the NoSQL database of Memcached, but its data can be stored persistently on the disk, solving the problem of no data loss after service

The fields used in this article are the emp table under scott, the default user in the Oracle database. sal represents the employee's salary, and deptno represents the Department number. I. Aggregate functions Aggregate functions are also called

I have heard about the word trigger (first in the database video). After reading the video, I did not have a deep understanding of such things as triggers, stored procedures, and transactions, logs and so on are not checked in detail, and there is