Database Administrator

Restrictions on table space that can be transferred: The table space technology cannot be applied to system tablespaces or objects owned by sys users. In the transmission tablespace, The tablespace must be self-contained. The self-contained table

The concept Data Model (Conceptual Data Model) is also known as the information Model. It is based on the object-link theory and expanded. It models the information Data from the user's perspective, it is mainly used for Conceptual Design of

Oralce: [Function description]: the current system time is automatically inserted into the getSysDate table every minute. [1. Create a test table] Create table getSysDate (test date ); [2. Create a stored procedure for scheduled execution] Create or

Today, we see this RMAN backup script in the company's database: Run {Allocate channel c1 type disk maxpiecesize = 2G;Allocate channel c2 type disk maxpiecesize = 2G;Backup incremental level 1 database format'/backup/osedb_osedb01/data/% d_DF _ % T _

Count the number of employees in the Department (number of employees = number of employees in the department + number of lower-level departments)Department table: Employee table: SQL statement: With Temp As( SelectT1.deptidAsId, t1.supdeptid

I. date type usage The date type subtraction only obtains the number of days.SQL> SELECT sysdate-(sysdate-1) FROM dual;SYSDATE-(SYSDATE-1)-------------------1Make an experiment:Create table t2 (d1 date, d2 date); -- create a tableInsert into T2

In fact, the main problem is to automatically start the Oracle service. There are also many examples on the Internet, but the success may not be achieved according to the example, next, let's take a look at the issues in the configuration process

Compiling invalid objects is one of the common tasks of DBAs and database developers. The following two methods are provided to capture errors during compilation. I. Current Database Version Information and invalid objects 1. view the current

In Oracle, the use of insert statements: 1. insert into Table 1 (column name 1, column name 2 ,......) Values (value 1, value 2 ,......) 2. insert into Table 1 (column name 1, column name 2 ,......) Select column name 1, column name 2 ,......

In practice, you need to replace the content of a field in a table in batches. The general thinking process is as follows: SELECT Replace str_replace UPDATE write In fact, this is a waste of resources and resource consumption. MYSQL has a

When creating a user,There is a default tablespace Parameter.You can view the viewDatabase_propertiesYou can see the corresponding information. SQL> select a. property_name, a. property_value from database_properties a where a. property_name like '%

SKIP OptionExcludes datafiles or archived redo logs from the backup set according to the criteria specified by the following keywords.Note: You can also specify this option in the backupSpec clause. OFFLINESpecifies that offline datafiles shocould

MongoDB usage notes 1. Installation Package http://www.mongodb.org/downloads Ii. server use LINUX version: ① Use tar-zxvfmongodb-linux-x86_64-1.2.4.tgz to decompress the installation package ② Mkdir-p/data/db create directory ③ Cd/data/db go to the

Ubuntu: After installing MongoDB and Python, how does Phython access the MongoDB database?Python is a simple programming language and the developed code is very readable.This article uses the Python driver called PyMongo driver and MongoDB to

Recently, a field value of a character type in the Oracle database was used to convert it to a number and save it to another new field. Oracle has a ToNumber function, however, it should be noted that this function can only convert the string format

The Oracle task here refers to the Oracle process or a series of business operations set for short, If the task execution time is too long, you usually need to connect to the database from the system background and execute the specified Oracle task.

Problem description: another small problem today: After adding two new fields to a table, the query speed is obviously slow. We suspect this is caused by row migration. If you try to move it, it will be OK. Impact of row migrationIf you read this

Understand Oracle, create users, and understand data types! Goal: Understand the orale Database I. Data Types in Oracle: Number Type: A) number indicates the number type, but if there is a decimal number, it must be written as follows: number

Oracle trigger simple table instance Create table dwuser. T1 (OLD_VALUE NUMBER (7,2 ),NEW_VALUE NUMBER (7,2 ),UP_DATE DATE );Create table dwuser. EMP (empno number (4 ),ENAME VARCHAR2 (10 BYTE ),JOB VARCHAR2 (9 BYTE ),Mgr number (4 ),Hiredate

1. After mysql is installed, the directory distribution in linux is as follows: Database Directory:/var/lib/mysql Configuration File:/usr/share/mysql (mysql. server command and configuration file) Related commands:/usr/bin (commands such as