Database Administrator

By default, for security reasons, the MySQL database in Linux shields remote access. However, in many cases, you need to access the remote database server at home or from a web application, which is quite troublesome. Step 1: Activate network

The MySoft_Data test of ORM is successful. It should be very useful. Model. e_cate c = new Model. e_cate ();C. fid = 1;C. name = "1 ";C. tmpid = "2222 "; DbSession session = new DbSession (new MySoft. data. mySql. mySqlProvider ("Server =

In Oracle databases, undo has three major functions: providing Consistent Read, Rollback Transaction, and Instance Recovery ).Consistent Read is relative to Dirty Read. Assume that a table T contains 10000 records. It takes 15 minutes to obtain all

A php program is downloaded and runs normally on Windows. However, when running on Linux, the system prompts that the table does not exist. It turns out that MySQL is not case sensitive in Windows, so it is normal. However, in Linux, because MySQL

Recently, I have re-installed the Ubuntu 10.10 system and need to re-compile and install Mysql. The source code version is 5.1.34. It's a tough task. I don't know what the 10.10 system has changed, and the software installation is so bad. Here we

There are a lot of useful things in Ubuntu 10.04, and so is the well-known MongoDB system. Related reading: Installing MongoDB on Ubuntu 10.04 As long as sudo apt-get install mongodb should be installed. However, you may find that it cannot be

After installing the Oracle software, you must configure listener to create a database in dbca, but netca reports the following error. Oracle Net Services Configuration:## An unexpected error has been detected by HotSpot Virtual Machine:## SIGSEGV (0

Installation environment: Ubuntu 10.04-desktop-i386 PostgreSQL 8.4 1. Install PostgreSQL Enter the following command Sudo apt-get install postgresql The system prompts you to install the required disk space. Enter "y". The installation program is

I. Physical Structure: 1. Data Files: the Oracle database contains several data files, which store database data, including tables and indexes. Several features of data files: 1) only one data file can be allocated to one database. 2) data files can

1. You need to modify the $ CRS_HOME/bin/racgvip script before running the root. sh script in the last step of crs installation. Otherwise, the vip cannot be started. The modification method is as follows: # Cd $ CRS_HOME/bin# Cp racgvip. old# Vi

Transactions and locks have the following features: A transaction is a unit of work, either completely or completely.Transactions ensure operation consistency and recoverabilityEach Transact-SQL statement can be a transaction.The actual transaction

The main body of Oracle functions is as follows: Create or replace function fn_get_agmt_bal (p_agmt_no varchar2)RETURN NUMBER ISV_bal NUMBER: = 0;-- If dbms_output takes effect during SQL/PLUS execution, run [SET SERVEROUTPUT ON] first

The biggest possible cause is that the database locks the table if the changed data is not committed! Therefore, when updating a table, do not use statements such as select * from a for update to easily lock the table. select *, t. rowid from t is a

Create a virtual service cluster for the user. Install liunx RedHat 4.3 32-bit + Oracle 10G in the vmware 5.3 bar virtual machine. Unfortunately, a client address conflicts with linux, and the database cannot be accessed after running for a while

After sorting out "Oracle database provides several different database startup and shutdown methods", I wrote an example when I went back. One problem occurs: ORA-12528: TNS: listener: all appropriate instances are blocking new connections So I went

I use ssh for remote configuration. The configuration is slightly different.1. Install MySQLSudo yum install mysql-serverSudo chgrp-R mysql/var/lib/mysqlSudo chmod-R 770/var/lib/mysqlSudo service mysqld start Set the password for the first

The field number is used when you create a table, The main problem is to use java to connect to the database, so there must be a pojo class, Like the number field, int Is Not Enough, long is difficult to convert, and it is prone to errors. Suddenly

Use rowid to simulate the restoration process of Bad blocks in the database: 1. Rowid definition (official website)A globally unique address for a row in a database.Oracle Database uses a rowid to uniquely identify a row. internally, the rowid is a

In 11g, Oracle introduced a new feature: adaptive cursor sharing. This feature is mainly used to improve the execution plan of SQL statements with variable binding. It also causes SQL statements with variable binding to generate multiple cursors. In

Oracle RAC client failover (failover). When using the TAF method, the client that has established a connection does not need to send a connection request again when the connected instance or node fails, the previous database operations can still be