Database Administrator

Due to work relations, you need to debug the postgreSQL source code. Just a colleague wrote such a document and posted it for sharing. To debug ipvs in Linux, perform the following steps:1. Install the Linux operating systemInstall gdb, Emacs, or

You can use select * from user_sequence and select * from all_tables to obtain the names of sequence and table for concatenation. The biggest fear is that the current account has insufficient permissions. It's a testing environment, so I can do

Recently I am working on a project. In this case, the database currently has three fields, year, month, and day, indicating year, month, and day. Now I need to merge them together, you can use this SQL syntax To_date (y. year | y. month | y. day,

Environment: Oracle 11g Problem description: execute the following statement in the database to view the tablespace utilization: Select d. tp_name tablespace name, e. contents type, e. status, e. extent_management, B. bytes size m, B. bytes-d.bytes

When we use a query statement, we often need to return the first few or a few rows of data in the middle. What should we do at this time? Don't worry, mysql already provides us with such a function. SELECT * FROM table LIMIT [offset,] rows | rows

ROW_NUMBER ()[Syntax] ROW_NUMBER () OVER (partition by COL1 order by COL2)[Function] indicates to group by COL1 and sort by COL2 within the Group. This value indicates the sequential number after sorting within each group (the continuous and unique

(1) obtain all the fields in the table. Select * from user_tab_columns where table_name = 'table name' (2) copy a table Create table user_temp as select * from user (3) associated sorting: When the sorting field of a table needs to be customized,

Data processing can be roughly divided into two categories:Online Transaction ProcessingOLTP(On-line transaction processing),Online Analytical ProcessingOLAP(On-Line Analytical Processing).OLTPIs the main application of traditional relational

In Oracle, single quotes have two functions: 1: The string is referenced by single quotes. 2: escape. The use of single quotes is proximity matching, that is, proximity principle. It is not easy to understand when single quotes act as escape

Ora-28056The following error occurs during database connection: ERROR:ORA-28056: failed to write audit records to Windows Event Logs Solution: You have cleared the records under the application in the Event Viewer (run-eventvwr) (you can export

Oracle login uard is so disgusting that it took so long ~ Next I will introduce the simplest installation method ~ 1. First, install two oracle databases with the same directory (you can select different directories). Because I use a VM, it is

Oracle optimizer has two Optimization methods: Rule-Based Optimization (RBO) and Cost-Based Optimization (Cost-Based Optimization, (for short, CBO). In Oracle8 and later versions, the CBO method is recommended for Oracle strong columns. RBO mode:

Get your rhlinux OK, let's go ~ 1. Download mysql server and client. Log onto the mysql website-> download, and select stable mysql server5.5. 2. set the Virtual Machine network, and select host-only here. Configure the vmnet1 network in the real

Set newpage none heading off space 0 PAGESIZE 0 trimout on trimspool on linesize 2500 colsep | feedback off termout off pages 0Set colsep |Alter session set nls_date_format = 'yyyy-mm-dd hh24: mi: ss ';Spool deltab. SQLSelect 'truncate table' |

How to obtain the auto-increment ID or the id just inserted in MySQLTo immediately obtain the id of the inserted record, the table must have an ID generated for an AUTO_INCREMENT column. $ SQL _addinfo =" Insert into contact_info_group set contact_

After a new MySQL connection arrives, a thread is allocated to the thread. If the server has Idle threads cached, use them directly. If no available cache thread exists, re-create a thread for this connection. /*Schedconnection that uses one thread

In Oracle queries, if there is no sorting, but you want to route the information of a specific value in a column to the front, use the decode (field, 'field value', number) of oracle) For example, if you want to forward the result of name = 'zhang

Create or replace function uf_timestamp_diff (endtime in TIMESTAMP, starttime in TIMESTAMP) RETURN INTEGER AS Str VARCHAR2 (50 ); Misecond INTEGER; Seconds INTEGER; Minutes INTEGER; Hours INTEGER; Days INTEGER; BEGIN Str: = to_char

Cause: the NLS_LANG parameter of the client connection is inconsistent with the NLS_CHARACTERSET In the DB. view the server parameters: Select * from nls_database_parameters t where t. parameter = 'nls _ CHARACTERSET'OrSelect * from v $

After the installation is complete (read the following link: Installing Oracle 10G R2 on CentOS 5.6), after you reactivate the instance, you will find that Oracle is not started on your own. This is normal, because Oracle Installation in Linux does