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SQL Data Integrity Commands

1. Primary Key Commands When the pk contains a single column example: create table t1 (f1 char(2) primary key, .... When the pk contains multiple columns exemple: create table t2 (                 f1 char(2), f2 char(2), f3 char(2),...,                 primary key (f1, f2)); ADD new constraints: alter table t2 add primary key (f1,f2); DROP constraints: alter table t2 drop primary key (f1,f2); 2. Foreign Key Commands

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Basic SQL

Data Definition Language (DDL) Creating a Table create table t (fd_name1 fd_type, fd_name2 fd_type, …);create table customer (ssn char(9), cname char(30), caddress char(30), amount number(10,2)); * field type: char(n)varchar(n)datenumber(x,n) Deleting a table drop table t;drop table customer; truncate table t;truncate table customer; /* delete all records in the table but not the field definitions */ Add A Column alter table t add (fx fd_type, fy fd_type);alter table customer add (zip char(5), phone char(10)); Modify Column Definition alter table table_name modify

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Nagios monitoring and SMS based alerts

1 Introduction The need for high availability of servers and services stems from their importance in daily business activities and linkages with the work. Using tools for monitoring servers and services is of great importance for the smooth functioning of the system as a whole and providing high availability. The system and the network administrators for the adequate administration of the system use different monitoring tools. Monitoring tools follow a large number of system parameters and notify the administrators about

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Installing Ubuntu Server Edition 14.04 as a Virtual Machine

Before installing Ubuntu Server 14.04, you need to install VirtualBox. To install VirtualBox on a laptop or desktop: Virtualization Technology needs to be enabled. On university laptops this must be enabled for 64-bit virtualization (You may need to request to have this feature turned on if you have a university laptop). You can download VirtualBox from virtualbox.org using a web browser (At the time this document was written, the latest version is VirtualBox 4.3.22 for Windows hosts -> x86/amd64). Please

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How to install and configure Postfix Linux Ubuntu?

Postfix is the default Mail Transfer Agent (MTA) in Ubuntu. It attempts to be fast and easy to administer and secure. It is compatible with the MTA sendmail. This section explains how to install and configure postfix. It also explains how to set it up as an SMTP server using a secure connection (for sending emails securely). Installation To install postfix run the following command: $ sudo apt-get install postfix Simply press return when the installation process asks questions, the

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How to install and configure MySQL Linux ubuntu?

MySQL is a fast, multi-threaded, multi-user, and robust SQL database server. It is intended for mission-critical, heavy-load production systems as well as for embedding into mass-deployed software. Installation To install MySQL, run the following command from a terminal prompt: $ sudo apt-get install mysql-server During the installation process you will be prompted to enter a password for the MySQL root user. Once the installation is complete, the MySQL server should be started automatically. You can run the following command from

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How to install HTTPD – Apache2 Web Server ubuntu?

Apache is the most commonly used Web Server on Linux systems. Web Servers are used to serve Web Pages requested by client computers. Clients typically request and view Web Pages using Web Browser applications such as Firefox, Opera, or Mozilla. The most common protocol used to transfer Web pages is the Hyper Text Transfer Protocol (HTTP). Protocols such as Hyper Text Transfer Protocol over Secure Sockets Layer (HTTPS), and File Transfer Protocol (FTP), a protocol for uploading and downloading files,

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How to install and configure server DNS linux ubuntu?

Installation At a terminal prompt, enter the following command to install dns: $ sudo apt-get install bind9 A very useful package for testing and troubleshooting DNS issues is the dnsutils package. To install dnsutils enter the following: $ sudo apt-get install dnsutils Configuration There a many ways to configure BIND9. Some of the most common configurations are a caching nameserver, primary master, and a as a secondary master. When configured as a caching nameserver BIND9 will find the answer to

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How to install Squid – Proxy Server linux ubuntu?

Squid is a full-featured web proxy cache server application which provides proxy and cache services for Hyper Text Transport Protocol (HTTP), File Transfer Protocol (FTP), and other popular network protocols. Squid can implement caching and proxying of Secure Sockets Layer (SSL) requests and caching of Domain Name Server (DNS) lookups, and perform transparent caching. Squid also supports a wide variety of caching protocols, such as Internet Cache Protocol, (ICP) the Hyper Text Caching Protocol, (HTCP) the Cache Array Routing Protocol

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How to install and configure DHCP server linux ubuntu?

The Dynamic Host Configuration Protocol (DHCP) is a network service that enables host computers to be automatically assigned settings from a server as opposed to manually configuring each network host. Computers configured to be DHCP clients have no control over the settings they receive from the DHCP server, and the configuration is transparent to the computer’s user. The most common settings provided by a DHCP server IP-Address and Netmask DNS WINS to DHCP clients include: However, a DHCP server can

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