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For adding MySQL virtual GENERATED COLUMNS in a table, we can use the same syntax as adding a column just adding “AS(expression)” after the data type. Its syntax would be as follows −SyntaxALTER TABLE table_name ADD COLUMN column_name AS(expression);Examplemysql> ALTER TABLE employee_data ADD COLUMN FULLName Varchar(200) AS(CONCAT_WS(" ", 'First_name', 'Last_name')); Query OK, 0 rows affected (0.49 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> Describe employee_data; +------------+--------------+------+-----+---------+-------------------+ | Field | Type | Null | Key | Default | Extra | +------------+--------------+------+-----+---------+-------------------+ | ID ... Read More
The KeyNotFoundException is thrown when a key you are finding is not available in the Dictionary collection.Let us see an example −Example Live Demousing System; using System.Collections.Generic; public class Demo { public static void Main() { try { var dict = new Dictionary() { {"TV", "Electronics"}, {"Laptop", "Computers"}, }; Console.WriteLine(dict["Pen Drive"]); } catch (Exception e) { Console.WriteLine(e); } } ... Read More
Followings are some basic differences between MySQL stored GENERATED COLUMNS and MySQL virtual GENERATED COLUMNS −In terms of Disk SpaceIf we see the difference in terms of disk space then virtual generated columns would not take any disk space. On the other hand, the stored generated column would take disk space.In terms of operationIf we see the difference in terms of operation then virtual generated columns are INPLACE operations which means that the table definition is changed without having to recopy all the data again. On the other hand, stored generated columns are a copy operation and it has the ... Read More
Use the orderby leyword to sort a list in ascending or descending order.The following is the list −List myList = new List(); myList.Add("truck"); myList.Add("bus"); myList.Add("bicycle"); myList.Add("motorbike");Now let us sort the list in descending order −myLen = from element in myList orderby element.Length descending select element;Here is the complete code −Example Live Demousing System; using System.Collections.Generic; using System.Linq; class Demo { static void Main() { List myList = new List(); myList.Add("truck"); myList.Add("bus"); myList.Add("bicycle"); myList.Add("motorbike"); var myLen = from element in myList ... Read More
The interface between a process and an operating system is provided by system calls. In general, system calls are available as assembly language instructions. They are also included in the manuals used by the assembly level programmers. System calls are usually made when a process in user mode requires access to a resource. Then it requests the kernel to provide the resource via a system calls.In general, system calls are required in the following situations −If a file system requires the creation or deletion of files. Reading and writing from files also require a system call.Creation and management of new ... Read More
Solaris is a Unix based operating system that was developed by Sun Microsystems and after its acquisition by Oracle it is known as Oracle Solaris. It is known for its scalability and its innovative features such as DTrace, ZFS, Time Slider etc.Solaris KernelThe kernel is the core of the operating system as its main function is to manage the hardware by allocating resources appropriately. Solaris is a microkernel design and it is not possible to create a monolithic Solaris kernel.Booting the kernel from a local disk in Solaris can be done using the following steps −Loading the bootblockReading and loading ... Read More
iOSThe iOS is the operating system created by Apple Inc. for mobile devices. The iOS is used in many of the mobile devices for Apple such as iPhone, iPod, iPad etc. The iOS is used a lot and only lags behind Android in terms of popularity.The iOS architecture is layered. It contains an intermediate layer between the applications and the hardware so they do not communicate directly. The lower layers in iOS provide the basic services and the higher layers provide the user interface and sophisticated graphics.The layered architecture of iOS is given as follows −AndroidAndroid is an operating system ... Read More
To display the last three elements from a list, use the Take() method. For reversing it, use the Reverse() method.Firstly, declare a list and add elements to it −List myList = new List(); myList.Add("One"); myList.Add("Two"); myList.Add("Three"); myList.Add("Four");Now, use the Take() method with Reverse() to display the last three elements from the list in reverse order −myList.Reverse().Take(3);The following is the code −Example Live Demousing System; using System.Linq; using System.Collections.Generic; public class Demo { public static void Main() { List myList = new List(); myList.Add("One"); myList.Add("Two"); myList.Add("Three"); ... Read More
MySQL LIKE operator is used to select data based on pattern matching. Similarly, we can use LIKE operator with views to select particular data based on pattern matching from the base table. To understand this concept we are using the base table ‘student_info’ having the following data −mysql> Select * from Student_info; +------+---------+------------+------------+ | id | Name | Address | Subject | +------+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Chandigarh | Literature | | 125 | Raman | Shimla | Computers | | 130 | ... Read More
Stopwatch is a class in C# to measure the elapsed time. Use it to calculate the time a function took to execute. It is found under System.Diagnostics.To get the elapsed time, firstly begin the Stopwatch −var sw = Stopwatch.StartNew();For elapsed ticks −long ticks = sw.ElapsedTicks;Let us see an example −Example Live Demousing System; using System.Linq; using System.Diagnostics; public class Demo { public static void Main() { var sw = Stopwatch.StartNew(); long ticks = sw.ElapsedTicks; Console.WriteLine(ticks); } }Output582