Database Administrator

1. Simple QueryA simple Transact-SQL query only includes the select list, FROM clause, and WHERE clause. They indicate the queried columns, the queried tables or views, and the search conditions.For example, the following statement queries the nick

Oracle beginners often ask this question. Here is a unified answer.1. If you have a certain database foundation and know what SQL is going on, you can skip to 2 even if you cannot write simple SQL statements. Otherwise, let's take a look at the

1. Obtain the installation package of Oracle9iShip_9204_linux_disk1.cpio.gzShip_9204_linux_disk2.cpio.gzShip_9204_linux_disk3.cpio.gz2. decompress and decompress the packageGunzip Cpio-idmv 3. Before installationYou can follow the instructions in

Mysql database backup can be performed in four ways:1. mysqldump2. Direct Copy (cp, tar, gzip, cpio)3. mysqlhotcopy4. synchronous ReplicationMysqldump generates text files that can be transplanted to other machines. By default, the file content

1. IntroductionSince PL/SQL cannot be used to develop applications for common users, you must use other languages or development tools. In Linux, what language or development tool should I use to develop Oracle database applications? This article

Mysql> set @ SQL _text: = 'select count (*) from test ';Query OK, 0 rows affected (0.00 sec)Mysql> prepare stmt from @ SQL _text;Query OK, 0 rows affected (0.04 sec)Statement preparedMysql> execute stmt;+ ---------- +| Count (*) |+ ---------- +| 0 |+

Just installed linux as 4.The first problem we face now is how to use mysql> [root @ server tmp] rmp-qa | grep mysql to check the current mysql version.I:When I input mysql in the command line, the following error occurs: Can't connect to local

Reset the root user password of the MySQL database 1. Stop the running MySQL process In Linux, run killall-TERM mysqld In Windows, if it is written as a service, you can run: net stop mysql. If it is not loaded as a service, you can directly

This article describes in detail the initial settings after installing the MySQL database in Ubuntu.1. It should be easy to install MySQL, and I don't think there is much problem in the installation, so I will not talk about it much. Next let's talk

When installing the current version of Oracle, the swap partition of Ubuntu 7.10 must be greater than 1 GB. Therefore, a swap file larger than 1 GB is used as the swap partition and deleted after use: > Dd if =/dev/zero of =/wherever/swap bs = 1024

Deploying multiple MySQL services on the same Linux server can effectively improve machine utilization. In addition, it is safer to classify different content into different services. MySQL provides mysqld_multi, but it is not used in actual

In Oracle databases, there are at least the following table spaces:1) SYSTEM tablespace. Each database contains a SYSTEM tablespace. When a database is created, the SYSTEM tablespace is automatically created. When the database is opened, the SYSTEM

Data structure:1. document is the most basic data organization form in MongoDB. Each document is organized in Key-Value (Key-Value Pair) mode. For example: {"Greeting": "Hello World! "} 2. A document can contain multiple Key-Value combinations. Each

(The executed commands are marked in green and the standby commands are marked in blue). Mongodb is a popular non-relational database recently. The following describes how to install linux on a virtual machine. Installation environment: Virtual

An error is returned when the production system needs to export data to an NFS directory. Bash-3.00 $ expdp \ '/as sysdba \' directory = bak_data_pump_dir schemas = epm_ha dumpfile = epm_ha.dmp logfile = epm_ha.log Export: Release 10.2.0.4.0-64bit

Query statements for all table structures in the PostgreSQL Column SELECT tablename FROM pg_tablesWHERE tablename not like 'pg %'AND tablename not like 'SQL _ %'Order by tablename; Query the field information of the t_appointment_apply

Database Version: Oracle 10.2.0.5 rac Operating system version: CentOS 5.6-64 1. Problems: 1) there are no errors in the background alter log 2) The mmon error message is as follows: * ** KEWRAFC: Flush slave failed, AWR Enqueue Timeout* ** 2013-02-1

Starting from Oracle 10 Gb, Oracle provides new features of Automatic SGA Management (ASMM for short, that is, Automatic Shared Memory Management. The so-called ASMM means that we no longer need to manually set the size of several memory pools such

B-tree indexes are the most common indexes (traditional indexes ).The simple creation method is: create index test_id_idx on test (id ).The following figure illustrates the B-Tree Index: ①: From top down, the first layer is the root node, the

Environment Introduction:OS: Oracle linux 5.6Redis: redis-2.6.8Master rac1 192.168.2.101Slave rac2 192.168.2.102:Http://redis.googlecode.com/files/redis-2.6.8.tar.gzInstall and configure redis master-slave Replication1. master node