Database Administrator

I started a project a few days ago. I used MySQL, but the project needed an Oracle database. After a month, I changed all the programs to an Oracle database, some differences between MySQL and Oracle are found during the operation. 1. mySQL can

MySQL triggers are basically described in every Mysql tutorial, but I found that the tutorials are about how to process data from other tables. When writing a trigger in MySQL to operate the column data of this table, the writing method is different

When PL/SQL is used for import, an error occurs: IMP-00032: the SQL statement exceeds the buffer length. IMP-00008: the exported file contains unrecognized statements. At first, I thought it was because the Large_Pool settings of the database

Oracle tables have nearly 11 million data records. In many cases, we need to perform string matching. in SQL statements, we usually use like to achieve our search goal. However, the actual test shows that the like efficiency is quite different from

1). MySQL installation layout in Ubuntu: /Usr/bin client program and mysql_install_db/Db database and log files (custom)/Var/run mysqld Server/Etc/mysql configuration file my. cnf/Usr/share/mysql Character Set, baseline program and error message/Etc/

Here we will first describe the database startup process: 1. when the instance/routine is started (nomount status), read the parameter file (PFILE in a text file or SPFILE in a server parameter file), allocate the SGA, start the background process,

I. in Linux   The Startup Script of app01 application server is as follows:   #! /Bin/sh ---- # Under aix or hpux #! /Bin/ksh If ['whoam '! = 'Weblogic ']; thenEcho 'login User error! 'Exit 9Fi Export srvName = app01Export adminUrl = http: // Manage

Split Block: During Hot Backup (that is, when the OS command copies the cp, the OS cp unit is not the data block but the OS block), the data Block is being modified by the user, that is, an Oracle Block contains multiple OS blocks. An OS-Level copy

Recently, when I was using redis Master/Slave, I did the following two things: 1. You want to analyze redis master-slave operations. All write operations are performed on the master node, and all read operations are performed on the master node. 2

In the shutdown status, the database only has the PLSExtProc service and is in an unknown state. The database is in the nomount status and has SID, SIDXDB, SID_XPT, and PLSExtProc services. The SID, SIDXDB, and SID_XPT services are in the

Usage: Require_once ("backdata. class. php ");$ Link = @ mysql_connect ("localhost", "Database Name", "password") or die ('could not connect to server .');Mysql_query ("use cms", $ link );Mysql_query ("set names utf8", $ link ); $ Dbbck = new

Regular Functions The following functions are applicable to any data type and use null values: • NVL (expr1, expr2) • NVL2 (expr1, expr2, expr3) • NULLIF (expr1, expr2) • COALESCE (expr1, expr2 ,..., exprn) the following functions are applicable to

• Group function:-type and syntax-use AVG, SUM, MIN, MAX, COUNT-use DISTINCT keyword in group function-NULL Value in group Function What is group function? The group function calculates the row set and provides a result for each group. Unlike a

Conversion functions In addition to Oracle data types, you can also use the American National Institute of Standards (ANSI), DB2, and SQL/DS data types to define columns in Oracle DB tables. However, Oracle Server converts these data types to

Oracle starts archive mode and related parameters, which involve the following parameters: log_archive_min_succeed_dest dynamic parameter log_archive_dest_state _ parameter Log_archive_format log_archive_dest_11. Enable archive Mode SQL> show

Abstract: rhel5.8, mysql, keepalived, and haproxy are used to build a cluster with high availability and load balancing. mysql binary replication is also used to maintain data consistency. Single Node failure is avoided, it also provides device

1. Table Name and column command rules: It must start with a letter and cannot exceed 30 characters. Oracle reserved words cannot be used. Only A-Za-z0-9 $ # and so on can be used. TABLE: partition table, table partition cluster index table

Even if relational databases are still very useful tools, their monopoly status for decades is coming to the fore. There are already countless NoSQL databases that can shake the status of relational databases. Of course, these NoSQL cannot

I have written an article about the performance problems caused by filter, which is written at the beginning: The word "filter" is confusing. a subnode, two subnodes, and three subnodes can be mounted at the next level .... Apply a subnode to filter

Requirements: 1. A customer table named Pers, whose primary key is the customer ID persnbr; 2. The seven columns in the pers table have foreign key constraints; 2. In the pers table, 0.1 million pieces of data are generated in batches (persnbr> = 100