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In fiber optic communication, signals are transmitted through an optical fiber. This is based upon certain characteristics of light, namely refraction and total internal reflection.RefractionWhen a light ray goes from a denser transmission medium to a rarer one or vice versa, then its direction changes at the interface of the two medium. This phenomenon is called refraction of light.The density of an optical medium is measured in refractive index. Higher the refractive index, denser it is.The angle between the incident ray and the normal is called angle of incidence Θi, while the angle between the refracted ray and the normal ... Read More
Optical fiber cables are transparent, flexible fibers made up of glass or plastic through which light waves can pass. A bunch of fiber optic cables is shown in the following diagram −Structure of a Fiber – Optic CableA cross section of a fiber optic cable reveals three parts −Core − It is the innermost portion of an optical fiber through which light propagates. It is cylindrical in shape and it made up of a flexible glass of high refractive index. The diameter of the core of a single mode fiber is 8 – 10 μm while multimode fibers are 50 ... Read More
As we know that CONCAT() function will return NULL if any of the argument of it is NULL. It means MySQL will return NULL if we pass column name, containing a NULL value, as one of the arguments of CONCAT() function. Following is an example of ‘Student’ table to explain it.ExampleIn this example, we are concatenating the values of two strings and at 5th row one, the value is NULL hence the concatenation result is also NULL.mysql> Select Name, Address, CONCAT(Name, ' Resident of ', Address)AS 'Detail of Student' from Student; +---------+---------+---------------------------+ | Name | Address | Detail ... Read More
Fiber optic cables are finding increasing usage due to a number of advantages over the traditional copper wires. However, there are a few flipsides in its usage too.Advantages of Fiber Optics Cables over Copper WiresFiber optic cables transmit data at much higher speed than copper wires. This is because the speed of light is greater than the speed of electrons.Fiber optic cables have a much larger bandwidth of over 60 Tbps in comparison to 10 Gbps bandwidth of copper wires.Fiber optic cables have very low attenuation. Repeaters need to be added only after every 50 km as compared to 5 ... Read More
The easiest way to extract the maximum numeric value from a string using regex is to −Use the regex module to extract all the numbers from a stringFind the max from these numbersFor example, for the input string −There are 121005 people in this city, 1587469 in the neighboring city and 18775994 in a far-off city.We should get the output −18775994We can use "\d+" regex to find all numbers in a string as \d signifies a digit and the plus sign finds the longest string of continuous digits. We can implement it using the re package as follows −import re ... Read More
MySQL allows us to pass only one argument to the CONCAT() function. In this case, MySQL returns the same argument as output. Following example will exhibit it −Examplemysql> Select Concat('Delhi'); +-----------------+ | Concat('Delhi') | +-----------------+ | Delhi | +-----------------+ 1 row in set (0.00 sec)
When there is a relationship between two entities of the same type, it is known as a recursive relationship. This means that the relationship is between different instances of the same entity type.Some examples of recursive relationship can be shown as follows −An employee can supervise multiple employees. Hence, this is a recursive relationship of entity employee with itself. This is a 1 to many recursive relationship as one employee supervises many employees.A person can have many children who are also persons. Hence, this is a recursive relationship of entity person with itself. This is a 1 to many recursive ... Read More
A string function called CONCAT() is used to concatenate two or more strings as a single string in MySQL.SyntaxCONCAT(String1,String2,…,StringN)Here, the arguments of CONCAT functions are the strings which need to be concatenated as a single string.Examplemysql> Select CONCAT('Ram','is','a','good','boy') AS Remarks; +---------------+ | Remarks | +---------------+ | Ramisagoodboy | +---------------+ 1 row in set (0.00 sec)
The distributed database management system contains the data in multiple locations. That can be in different systems in the same place or across different geographical locations.As shown in the below example −The database is divided into multiple locations and stores the data in Site1, Site2, Site3 and Site4.The advantages and disadvantages of Distributed database management systems are as follows −Advantages of DDBMSThe database is easier to expand as it is already spread across multiple systems and it is not too complicated to add a system.The distributed database can have the data arranged according to different levels of transparency i.e data ... Read More
Open source databases are those databases who have an open source code i.e anyone may view the code, study it or even modify it. Open source databases could be relational (SQL) or non relational (NoSQL).Why use Open Source Databases?It is quite expensive to create and maintain a database for any company. A huge chunk of the total software expenditure is used to handle databases. So, it is feasible to switch to low cost open source databases. This saves companies a lot of money in the long run.Open Source Databases in useThere many different open source databases in the market. All ... Read More