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The HTML ondragenter event attribute is triggered when a draggable element or text enters a valid drop target in an HTML document.SyntaxFollowing is the syntax −ExampleLet us see an example of HTML ondragenter event Attribute − Live Demo body { color: #000; height: 100vh; background-color: #FBAB7E; background-image: linear-gradient(62deg, #FBAB7E 0%, #F7CE68 100%); text-align: center; } .drop-target { display: inline-block; width: 150px; height: 150px; border: 2px solid #FFF; ... Read More
Clustering systems are similar to parallel systems as they both have multiple CPUs. However a major difference is that clustered systems are created by two or more individual computer systems merged together. There are two types of Clustering systems i.e. asymmetric and symmetric clustering systems. Details about these are given as follows −Asymmetric Clustering SystemIn this system, one of the nodes in the clustered system is in hot standby mode and all the others run the required applications. The hot standby mode is a failsafe in which a hot standby node is part of the system . The hot standby ... Read More
Actually ROLLUP and ORDER BY are mutually exclusive in MySQL hence it is not a good practice to use both of them in a query. But still, if we use ROLLUP in ORDER BY then the main disadvantage is that the summary rows would get sorted along with the rows they are calculated. It is also significant to notice that the sort order will decide the position of summary rows.The summary rows would be at the beginning of ascending order and at the end of descending order. Consider the following example to understand it more clearly −mysql> Select * from ... Read More
In the case, where we use explicit sort order (ASC or DESC) with column names in the GROUP BY list along with the “WITH ROLLUP” modifier, the summary rows added by ROLLUP still appear after the rows from which they calculated regardless of the sort order.As we know that the default sort order is ascending hence in the example below if we will not use any explicit sort order then the output would be as follows −mysql> Select sr, SUM(Price) AS Price from ratelist Group by sr with rollup; +-----+-------+ | sr | Price | +-----+-------+ | 1 | ... Read More
We can also use the BEGIN statement to start a new transaction. It is the same as the START TRANSACTION statement.Examplemysql> BEGIN; Query OK, 0 rows affected (0.00 sec) mysql> INSERT INTO Marks Values(1, 'Aarav', 'History', 40); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Marks Values(2, 'Harshit', 'History', 48); Query OK, 1 row affected (0.00 sec) mysql> ROLLBACK; Query OK, 0 rows affected (0.04 sec)In this example, the transaction is initiated by the BEGIN Statement rather than START TRANSACTION statement. Two INSERT statements are then executed followed by a ROLLBACK statement. ROLLBACK statement will ... Read More
In the electromagnetic spectrum, waves within the frequencies 1GHz to 300GHz are called microwaves.Features of MicrowavesMicrowaves travel in straight lines, and so the transmitter and receiver stations should be accurately aligned to each other.Microwave propagation is line – of – sight propagation. So, towers hoisting the stations should be placed so that the curvature of the earth or any other obstacle does not interfere with the communication.Since it is unidirectional, it allows multiple receivers in a row to receive the signals without interference.Microwaves do not pass through buildings. So, indoor receivers cannot be used effectively.Microwaves are often refracted by the ... Read More
By using \G at the end of MySQL statement, it returns the output in a vertical format rather than a tabular format. Consider the example below −mysql> Select curdate(); +------------+ | curdate() | +------------+ | 2017-11-06 | +------------+ 1 row in set (0.00 sec) mysql> Select CURDATE()\G *************************** 1. row *************************** CURDATE(): 2017-11-06 1 row in set (0.00 sec)From the example above, the difference of using \G at the end of the MySQL statement can be understood. It returns the same output in a vertical format rather than a tabular format.
A communication satellite is an artificial satellite that acts as a large repeater in the sky. It receives signals from the source transmitter, amplifies using transponders, and relays them to the receiver. Thus, it creates a communication channel between locations of the earth that would not have been able to communicate due to long distance or obstruction by earth’s curvature.Communication satellites may be owned by government or private organizations. Presently, there are more than 2000 communication satellites in the sky. Some of its uses are −InternetMilitary operationsTelevisionTelephoneRadioCommunication satellites are broadly categorized into three types depending upon the orbit in which ... Read More
The kernel data structures are very important as they store data about the current state of the system. For example, if a new process is created in the system, a kernel data structure is created that contains the details about the process.Most of the kernel data structures are only accessible by the kernel and its subsystems. They may contain data as well as pointers to other data structures.Kernel ComponentsThe kernel stores and organizes a lot of information. So it has data about which processes are running in the system, their memory requirements, files in use etc. To handle all this, ... Read More
A computer system uses many devices, arranged in different ways to solve many problems. This constitutes a computing environment where many computers are used to process and exchange information to handle multiple issues.The different types of Computing Environments are −Let us begin with Personal Computing Environment −Personal Computing EnvironmentIn the personal computing environment, there is a single computer system. All the system processes are available on the computer and executed there. The different devices that constitute a personal computing environment are laptops, mobiles, printers, computer systems, scanners etc.Time Sharing Computing EnvironmentThe time sharing computing environment allows multiple users to share ... Read More