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Operating Systems have become quite complex and multifaceted with the advancement of time. However, that also means it is getting more and more difficult to design operating systems that satisfy all the specifications required these days. There are no complete solutions possible for design problems, but some approaches are more successful than others.Design Requirements in Operating SystemThe design requirements are quite hard to specify in an operating system. They are basically divided into two parts: User design requirements and System design requirements. Details about these are given as follows −User Design RequirementsThe operating system should be convenient, easy to use, ... Read More
It can be done with the help of the following statement −mysql> select * from information_schema.triggers where -> information_schema.triggers.trigger_schema like '%query%'\G *************************** 1. row *************************** TRIGGER_CATALOG: def TRIGGER_SCHEMA: query TRIGGER_NAME: trigger_before_delete_sample EVENT_MANIPULATION: DELETE EVENT_OBJECT_CATALOG: def EVENT_OBJECT_SCHEMA: query EVENT_OBJECT_TABLE: sample ACTION_ORDER: 1 ACTION_CONDITION: NULL ACTION_STATEMENT: BEGIN SET @count ... Read More
We can use the DISTINCT clause on more than columns in MySQL. In this case, the uniqueness of rows in the result set would depend on the combination of all columns.ExampleConsider the following table ‘testing’ having 10 rows −mysql> select * from testing; +------+---------+---------+ | id | fname | Lname | +------+---------+---------+ | 200 | Raman | Kumar | | 201 | Sahil | Bhalla | | 202 | Gaurav | NULL | | 203 | Aarav | NULL | | 204 | Harshit | Khurana | | 205 | Rahul ... Read More
A microkernel is the minimum software that is required to correctly implement an operating system. This includes memory, process scheduling mechanisms and basic inter-process communication.A diagram that demonstrates the architecture of a microkernel is as follows −In the above diagram, the microkernel contains basic requirements such as memory, process scheduling mechanisms and basic interprocess communication. The only software executing at the privileged level i.e. kernel mode is the microkernel. The other functions of the operating system are removed from the kernel mode and run in the user mode. These functions may be device drivers, file servers, application interprocess communication etc.The ... Read More
When we use the GROUP BY clause in the SELECT statement without using aggregate functions then it would behave like the DISTINCT clause. For example, we have the following table −mysql> Select * from testing; +------+---------+---------+ | id | fname | Lname | +------+---------+---------+ | 200 | Raman | Kumar | | 201 | Sahil | Bhalla | | 202 | Gaurav | NULL | | 203 | Aarav | NULL | | 204 | Harshit | Khurana | | 205 | Rahul | NULL | | 206 | ... Read More
The entire operating system works in the kernel space in the monolithic system. This increases the size of the kernel as well as the operating system. This is different than the microkernel system where the minimum software that is required to correctly implement an operating system is kept in the kernel.A diagram that demonstrates the architecture of a monolithic system is as follows −The kernel provides various services such as memory management, file management, process scheduling etc. using function calls. This makes the execution of the operating system quite fast as the services are implemented under the same address space.Differences ... Read More
We can find all the triggers associated with a particular table with the help of the following query −mysql> Select * from INFORMATION_SCHEMA.TRIGGERS WHERE TRIGGER_SCHEMA = 'query'AND EVENT_OBJECT_TABLE = 'Student_info'\G *************************** 1. row *************************** TRIGGER_CATALOG: def TRIGGER_SCHEMA: query TRIGGER_NAME: studentinfo_after_delete EVENT_MANIPULATION: DELETE EVENT_OBJECT_CATALOG: def EVENT_OBJECT_SCHEMA: query EVENT_OBJECT_TABLE: student_info ACTION_ORDER: 1 ACTION_CONDITION: NULL ... Read More
System programs provide an environment where programs can be developed and executed. In the simplest sense, system programs also provide a bridge between the user interface and system calls. In reality, they are much more complex. For example: A compiler is a complex system program.The user view of the system is actually defined by system programs and not system calls because that is what they interact with and system programs are closer to the user interface.An image that describes system programs in the operating system hierarchy is as follows −In the above image, system programs as well as application programs ... Read More
The Main method is the entry point for all C# programs. It states what the class does when executed.The valid variant of Main() is −static void Main(string[] argsHere,static − the object is not needed to access static membersvoid − return type of the methodMain − entry point for any C# program. Program execution begins here.string[] args − for command line arguments in C#.ExampleHere is an example −using System; namespace Program { public class Demo { public static void Main(string[] args) { Console.WriteLine("Welcome!"); Console.ReadKey(); } } }
Main ThreadThe first thread to be executed in a process is called the main thread. When a C# program starts execution, the main thread is automatically created.Child ThreadThe threads created using the Thread class are called the child threads of the main thread.Here is an example showing how to create a main and child thread −Example Live Demousing System; using System.Threading; namespace Demo { class Program { static void Main(string[] args) { Thread th = Thread.CurrentThread; th.Name = "MainThread"; Console.WriteLine("This is {0}", th.Name); Console.ReadKey(); } } }OutputThis is MainThread