eduguru The DEFAULT constraint is used to set a default value for a column. In the below example City column has the default value Sandnes CREATE TABLE Persons ( ID int NOT NULL, LastName varchar(255) NOT NULL, FirstName varchar(255), Age int, City varchar(255) DEFAULT ‘Sandnes’); The default value will be added to all new records if no other value is specified. Example of default constraint Example … Read more
What is SQL Injection? SQL Injection is an attack that poisons dynamic SQL statements to comment out certain parts of the statement or appending a condition that will always be true. It takes advantage of the design flaws in poorly designed web applications to exploit SQL statements to execute malicious SQL code. Data is one … Read more
How to Hack a Website Here, you will learn how to hack websites, and we will introduce you to web application hacking techniques and the countermeasures you can put in place to protect against such attacks. What is a web application? What are Web Threats? A web application (aka website) is an application based on the client-server … Read more
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