Database Administrator

Oracle Foreign keys only have cascade deletion and no Cascade update, but sometimes such functions may be required in the system, so the implementation process is recorded here. There are two constraints in Oracle: latency constraint and non-latency

The mongo official website has provided a detailed introduction to mongoDB installation and configuration. Here we only list some scripts for mongoDB configuration, for your reference only. -- Enter the bin directoryMongod-dbpath "d: \ mongodb" --

1. Install the configuration Install Mysql on both servers in the/usr/local/mysql directory (the installation steps are omitted. Refer to the relevant documentation ), the IP addresses of the two servers are 192.168.0.1 and 192.168.0.2. We use 192.16

Oracle indexes are organized and stored in the form of a Balance Tree: stores the value of the index column, a part of the rowid (file number, block number, row number) The following is an example: 1, create table test (id int, name varchar2 (20

We all know that the controlfile records information about each archivelog. Of course, after deleting these physical files in the OS The archivelog information is still recorded in the controlfile. the logs are displayed visually in the Oracle OEM

The following is my summary and my understanding about Oracle backup: 1. The data block size in Oracle is usually an integer multiple of the OS block size. The database is always available when the data file is directly copied to the backup media

When checking the disk space used by the database files, we found that the undo tablespace used as much as 4 GB this weekend. Up to 24 GB! According to the normal volume of things, it will not grow so fast. Now there are a few GB of memory left on

Select grouping (vsaltype) as sq, Vsaltype | 'subtotal 'vsaltype, Sum (amount) as amount, ''Vvin, ''Vpropertywh, ''Vpropertywhdesc FromSPTW90_INVENTORY_NCS_TMP Group by rollup (vsaltype) The result is as follows: : Analysis conclusion: Grouping: If

For more information, see How-to handle and respond to mouse double clicks . When you double-click a row of a table, popup and sub-table data are displayed in popup. Add the attribute at the end of the primary table ClientListener captures the

The simulated server suddenly loses power, the database is lost, and the transaction cannot be recovered from the rollback failure.The database status is as follows:SQL> select instance_name, status from v $ instance;INSTANCE_NAME STATUS-------------

1. Currently, there is only one control file. We plan to add three to ensure security. SQL> select name from v $ controlfile; NAME -------------------------------------------------------------------------------- + DATA/tyolap/controlfile/current.256

Upgrade the database from 10.2.0.1.0 to 10.2.0.5.0, start the database, error: ORA-01092: Oracle routine termination, forced disconnection.View the alert file.ORA-00704: bootstrap process failure.ORA-39700: database must be opened with UPGRADE

1: An error occurred while restarting the database today: SQL> startup mountORA-03113: end-of-file on communication channel Take a look at alert. log:...PMON started with pid = 2, OS id = 7359PSP0 started with pid = 3, OS id = 7361MMAN started with

The term "View" is too abstract. At first glance, you don't understand what it means, but you don't even know what it means. In fact, you will suddenly realize what it means. The difference between a table and a view is that a table occupies the

1. Create the same directory as the 9i data file, control file, and redo file on the target server where Oracle 10g software is installed (the data files of the two databases must be in the same location) 2. Shut down the 9i source database, copy

Numeric FunctionsROUNDTRUNCMODCEILPowerROUND (column name | expression, n)Rounded to n digits after the decimal pointIdle> select round (458.734, 0), round (458.734, 1), round (458.734,-1) from dual; ROUND (458.734, 0) ROUND (458.734, 1) ROUND (458.7

Processing of date functionsIf you are uncomfortable with the date format of the current system, you can modify the display format of the current session.Idle> alter session set NLS_DATE_FORMAT = 'yyyy-MM-DD HH24: MI: ss '; Session altered. Idle>

I. Installation1. Download The mysql-5.1.54.tar.gz and unzip it to/root/mysql/mysql-5.1.54 directory2. Download The ahiguti-HandlerSocket-Plugin-for-MySQL-1.0.6-94-g98b14c3.tar.gz and unzip it to the/root/mysql/ahiguti-HandlerSocket-Plugin-for-MySQL-

Hive provides two data import methods. 1. import from the table: Insert overwrite table test Select * from test2; 2 import from file: 2.1 import from a local file: Load data local inpath '/Hadoop/aa.txt' overwrite into table test11 2.2 import

PostgreSQL is a free object-relational database server (Database Management System), which is issued under a flexible BSD-style license. Compared with other open-source database systems (such as MySQL and Firebird), it provides a choice for