What is Docker? Docker is a platform for building, running and shipping applications in a consistent manner. So, if your application works on your development machine, it can run and function the same way on other machines. With Docker, we Read more…
The internet is made up of end-hosts, links and routers. Data is delievered hop-by-hop over each link in turn. Data is delivered in packets. A packet consistes of the data we want to be delivered, along with a header that Read more…
A JOIN clause is used to combine rows from two or more tables, based on a related column between them. There are four types of join in MySQL: INNER JOIN: Returns records that have matching values in both tables LEFT JOIN: Returns Read more…
Atomicity: operations in a transaction either all succeed or all fail. Consistency: The database always transitions from one consistent state to another consistent state. The integrity of the database is not broken before the transaction starts and after the transaction Read more…
TRUNCATE TRUNCATE Command is a Data Definition Language operation. It is used to remove all the records from a table. It deletes all the records from an existing table but not the table itself. The structure or schema of the table is Read more…
dpkg is short for Debian package, a package management system developed specifically for the Debian operating system to install, update and remove software. All Linux systems derived from “Debian” use dpkg, for example “Ubuntu”. dpkg [option] <action> Options:-i: Install package-r: Read more…
dpkg -l will list information about all installed packages on your system. In combination with grep, you can filter out what you want. e.g. dpkg -l | grep ftp The first column of the output is usually two letters, representing Read more…
Locate: Lookups are based on the database of the file system. The database is updated by the updatedb program. updatedb is created by the cron daemon and runs periodically. You can also generate it manually with the updatedb command. This Read more…
Database and Table · Create Database CREATE DATABASE <database name>; CREATE DATABASE shop; · Create Table CREATE TABLE <table name> (<column name> <data type> <constrains>, <column name> <data type> <constrains>, …, <constrains of the table>,<constrains of the table>,…); CREATE TABLE Read more…
A Controller servlet may perform either a forward or a redirect operation at the end of processing a request. It is important to understand the difference between these two cases, in particular with respect to browser reloads of web pages Read more…