eduguru What is VPN, and why does Home Ministry want to ban it? A Home Affairs Committee has urged the Indian government to ban VPN services across India for security reasons. Virtual Private Network or VPN is gaining the limelight in India, with alleged reports hinting that the government might soon ban their use in the … Read more
How to Hack a Web Server Most websites store valuable information such as credit card numbers, email addresses, and passwords, etc. This has made them targets to attackers. Defaced websites can also be used to communicate religious or political ideologies etc. Here, we will introduce you to web server hacking techniques and how you can … Read more
DoS – Denial of Service Attack What is DoS Attack? DOS is an attack used to deny legitimate users access to a resource such as accessing a website, network, emails, etc., or making it extremely slow. DoS is the acronym for Denial of Service. This type of attack is usually implemented by hitting the target resource such as … Read more
WPS Spreadsheets WPS Spreadsheets belongs to WPS Office, a complete office suite for Windows, macOS, and Linux. Apart from Spreadsheets, the suite also includes WPS Presentation, WPS Writer, and a PDF editor. The main advantage of WPS Spreadsheets is its high compatibility with Excel files because it supports XLS, XLSX, and CSV. Exporting spreadsheets to PDF is available but the output file will contain a … Read more
Preventing duplicate cron job executions I feel like sometimes cron jobs create more problems than they solve. It’s not the fault of the cron, but rather the jobs being executed. As the job is not yet completed and started the other cronjob. This leads to duplicate instances of cron jobs running for the same task. … Read more
MySQL CHECK Constraint The CHECK the constraint is used to limit the value range that can be placed in a column. If you define a CHECK constraint on a column it will allow only certain values for this column. If you define a CHECK constraint on a table it can limit the values in certain columns based on values in other … Read more
MySQL PRIMARY KEY Constraint The PRIMARY KEY constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values. A table can have only ONE primary key; and in the table, this primary key can consist of single or multiple columns (fields). PRIMARY KEY on CREATE TABLE The following SQL … Read more
UNIQUE Constraint The UNIQUE constraint ensures that all values in a column are different. Both the UNIQUE and PRIMARY KEY constraints provide a guarantee for uniqueness for a column or set of columns. A PRIMARY KEY constraint automatically has a UNIQUE constraint. However, you can have many UNIQUE constraints per table, but only one PRIMARY KEY constraint per table. This constraint ensures that all values inserted into the column … Read more
NOT NULL Constraint By default, a column can hold NULL values. The “NOT NULL constraint” enforces a column to NOT accept NULL values. This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field. This constraint specifies that … Read more
MySQL Constraints SQL constraints are used to specify rules for data in a table. The constraint in MySQL is used to specify the rule that allows or restricts what values or data will be stored in the table. They provide a suitable method to ensure data accuracy and integrity inside the table. It also helps … Read more