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Relational Database - Codd's Rules
Relational Database - Codd's Rules !!!A relational database management system (RDBMS) is a database management system (DBMS) that is based on the relational model as introduced by E. F. Codd. Most popular commercial and open source databases currently in use are based on the relational database model.A short definition of an RDBMS may be a DBMS in which data is stored in the form of tables and the relationship among the data is also stored in the form of tables.
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">Codd's Rules- All database management must take place using the relational database's innate functionality
- All information in the database must be stored as values in a table
- All database information must be accessible through the combination of a table name, primary key and column name.
- The database must use NULL values to indicate missing or unknown information
- The database schema must be described using the relational database syntax
- The database may support multiple languages, but it must support at least one language that provides full database functionality (e.g. SQL)
- The system must be able to update all updatable views
- The database must provide single-operation insert, update and delete functionality
- Changes to the physical structure of the database must be transparent to applications and users.
- Changes to the logical structure of the database must be transparent to applications and users.
- The database must natively support integrity constraints.
- Changes to the distribution of the database (centralized vs. distributed) must be transparent to applications and users.
- Any languages supported by the database must not be able to subvert integrity controls.
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">Tags: database, table, DBMS, RDBMS, columns, Codd, E. F. Codd, rules, oracle, data================================================ O************************O***********************O
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Apt-Get command line tool
Apt-Get command line tool(Ubuntu's Advanced Packaging Tool) !!!
The apt-get command is a powerful command-line tool used to work with Ubuntu's Advanced Packaging Tool (APT) performing such functions as installation of new software packages, upgrade of existing software packages, updating of the package list index, and even upgrading the entire Ubuntu system.
*Install package
#sudo apt-get install packagename
*Remove Package
#sudo apt-get remove packagename
*Install Multiple Packages
#sudo apt-get install packagename1 packagename2 packagename3
*Update the Package Index
#sudo apt-get updateThe APT package index is essentially a database of available packages from the repositories defined in the /etc/apt/sources.list file.
*Upgrade the system
#sudo apt-get upgrade
*Read Debian APT User Manual
#sudo apt-get helpTags: apt get apt-get advanced packaging tool install remove upgrade update help ubuntu linux unix package-management
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Port Numbers - Linux
PORTS NUMBERS : Just as the physical address (MAC address) and the logical address (IP address) helps to route the traffic to a particular machine on a network, it is the port that identifies which service on the machine this traffic is destined to.
List of ports : /etc/servicesA port on a specific computer is called a socket. It can be open, closed, listening or have a connection established.
###Important PORT NUMBERS to remember:20 - FTP - data transfer21 - FTP - control (command)22 - SSH23 - Telnet25 - SMTP37 - Time43 - WHOIS42 - WINS53 - DNS67 - BOOTp68 - DHCP69 - TFTP79 - FINGER80 - HTTP (WWW)88 - Kerberose101 - HOSTNAME110 - POP3111 - rpcbind119 - NNTP123 - NTP (Time)137 - NetBios (nmbd)139 - NetBios ( Samba)143 - IMAP/Dovecot161 - SNMP180 - RIS220 - IMAP3389 - LDAP443 - HTTPs500 - Internet Key Exchange (IKE), IPSec520 - RIP546 - DHCPV6 client547 - DHCPV6 server554 - rtsp(Real Time Stream Protocol, Audio/Video)631 - Printing (ipp)744 - Flexlm901 - SWAT953 - rndc993 - IMAPSecure995 - POPs999 - POP over SSL/TLS2049 - NFS2082 - CPANEL2083 - CPANEL Secure SSL/TLS2086 - CPANEL WHM2087 - CPANEL WHM Secure/SSL2095 - CPANEL Webmail2096 - CPANEL Webmail Secure/SSL2222 - Direct Admin Control Panel2401 - CVSP server3268 - AD Global Catalog3269 - AD Global Catalog over SSL3306 - MySQL Server3389 - Terminal services (rdp-remote desktop protocol)4643 - Virtusso Power Panel(6000 - X116063)8443 - Pleask Control Panel9999 - Urchin10000- Webmin Control Panel21018- Skype
TAG: port, portnumber, port-numbers, tcp, udp, network, service, services, linux, socket, communication, transmission, dataflow, rhce, ubuntu, unix, red hat, red-hat, redhat
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