Database Administrator

Query the character set of the current databaseBYS @ bys1> select userenv ('language ') from dual;USERENV ('language ')----------------------------------------------------AMERICAN_AMERICA.AL32UTF8BYS @ bys1> select * from

[Client] [Mysqld] Collation_server = utf8_general_ci Character_set_server = utf8 [Mysql] [Mysqldump] 3. Data Table Encoding /*! 40101 SET @ saved_cs_client = @ character_set_client */; /*! 40101 SET character_set_client = utf8 */; CREATETABLE

1. easy solution for profit calculation When the product design is defective, profit calculation will be a nightmare, because the commodity purchase price is actually changed (the prices for different purchases at different times will be different),

Today, I checked the network connection status (netstat/ano) on the server and saw a bunch of TIME_WAIT connections, all of which were connected to port 1433. Obviously this is a malicious connection, therefore, to ensure the security of the server

Troubleshooting IO-related wait: Determine the true importance of IO wait events: The following two real cases illustrate why the "Wait Time" and "Service Time" sections are important for analyzing database

1. Explain the differences between cold backup and hot backup and their respective advantagesAnswer: Hot Backup is applicable to databases in the archive mode. When the database is still in the working state, it is backed up. Cold backup refers to

-- Use the regular expression with t as (select 'guangdong, Guangxi, Hainan, Guizhou, Yunnan 'str from dual) SELECT REGEXP_SUBSTR (str,' [^,] + ', 1, ROWNUM) province FROM tCONNECT by rownum PROVINCE ------------------------------ Guangdong,

I believe everyone has encountered the lock table. I think everyone knows the unlock method, but the killing processes are sometimes low-level. We use stored procedures to implement this function, it becomes very simple. 1. Create a view and query

 ========================================================== ========================================================== 1: how to classify backups Logical backup: exp/imp Physical backup: RMAN backup Full backup/incremental backup

How to diagnose job execution failure 1. Check whether the job can be executed.Make sure that the job_queue_processes parameter in init. ora is set to a value greater than 0.Show parameter job_queue_processes 2. Check whether an error occurred

So that we can make a persuasive judgment. Description Wait for "SQL * Net message from client". The SQL * Net package that receives the statement request "parse/execute. Parse the SQL * Net package. Wait for "latch free"

It is very convenient for CHAR to store fixed-length data, and the indexing efficiency of CHAR fields is high. For example, if char (10) is defined, no matter whether the data you store reaches 10 characters, it takes up to 10 characters. To store

Aggregate functions for computing in SQL statements: COUNT (*): calculates the number of tuples. COUNT ( SUM/AVG/MAX/MIN (): Calculate the SUM, average, maximum, and minimum values of a column (numeric type) Let's analyze the types of

After the database is upgraded, how can I determine whether the upgrade is successful? Function rounding? Returns a value rounded to the specified number of decimal places.Number: value to be processedThe number of decimal places is set to select

Cursor definition: --- Use declare -- to define a cursor and extract all data from tab_stu. cursor c_tab_stu is select * from

What is Pl/SQL: -- Declare/* Statement of PL/SQL: declare the variables, types, and cursors used by PL/SQL, as well as local stored procedures and

1. Export the. SQL file, open the doscommand line, run cd to enter the bin directory of mysql, and run Mysqldump-uroot-p your Password Database Name> D:/export file name. SQLFor example: Mysqldump-uroot-p123456 listener> D:/listener. SQL Ii.

Flashback query is a flashback Based on the undo tablespace. The related parameters are as follows: SQL> show parameter undo NAME TYPE VALUE-----------------------------------------------------------------------------Undo_management string

The storage engine layer can decide how to lock data by accepting the lock type passed by the Server layer.Table locks are implemented at the Server layer. If MyISAM is not implemented by itself, the table locks passed at the Server layer are used

   I. symptom   A netizen's production Database Listener cannot be started. It has been re-built N times and configured and the parameter is OK. However, the following error is reported during startup:     Error listening on :( ADDRESS =