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If a column in an R data frame has only two values 0 and 1 then we call it a binary column but it is not necessary that a binary column needs to be defined with 0 and 1 only but it is a general convention. To detect a binary column defined with 0 and 1 in an R data frame, we can use the apply function as shown in the below examples.ExampleConsider the below data frame − Live Demox1
Problem:You want to display open cursors in Oracle.SolutionWe can query the data dictionary to determine the number of cursors that are open per session. "V$SESSION" provides a more accurate number of the cursors currently open than "V$OPEN_CURSOR".Exampleselect a.value , c.username , c.machine , c.sid , c.serial# from v$sesstat a , v$statname b , v$session c where a.statistic# = b.statistic# and c.sid = a.sid and b.name = 'opened cursors current' and a.value != 0 and c.username IS NOT NULL order by 1, 2;The OPEN_CURSORS initialization parameter determines the maximum number of cursors a session can have open.Read More
Problem:You want to identify the SQL statements responsible for the most waits in your database.SolutionWe can use below SQL statement to identify SQL causing problem.The below query will rank SQL statements that ran during the past 30 minutes and display them as per the total time waited by each query.ExampleSELECT ash.user_id, u.username, s.sql_text, SUM(ash.wait_time + ash.time_waited) ttl_wait_time FROM v$active_session_history ash, v$sqlarea s, dba_users u WHERE ash.sample_time BETWEEN sysdate - 60/2880 AND sysdate AND ash.sql_id = s.sql_id AND ash.user_id = u.user_id GROUP BY ash.user_id, s.sql_text, u.username ORDER BY ttl_wait_time ;When you have a performance ... Read More
With INNER JOIN only the matching elements are included in the result set. Non-matching elements are excluded from the result set.With LEFT OUTER JOIN all the matching elements + all the non-matching elements from the left collection are included in the result set.Let us understand implementing Left Outer Join with an example. Consider the following Department and Employee classes. Notice that, Employee Mary does not have a department assigned. An inner join will not include her record in the result set, where as a Left Outer Join will.Examplestatic class Program{ static void Main(string[] args){ var result = Employee.GetAllEmployees() ... Read More
Reflection is the process of describing the metadata of types, methods and fields in a code. The namespace System.Reflection enables you to obtain data about the loaded assemblies, the elements within them like classes, methods and value types. There are numerous classes of System.Reflection but the most commonly used ones are Assembly, AssemblyName, ConstructorInfo, MethodInfo, ParameterInfo, EventInfo, PropertyInfo, and MemberInfo.Examplestatic void Main(string[] args){ TypeInfo myType = typeof(TextInfo).GetTypeInfo(); IEnumerable properties = myType.DeclaredProperties; IEnumerable methods = myType.DeclaredMethods; Console.WriteLine(myType); Console.WriteLine(properties); Console.WriteLine(methods); StringBuilder strBuilder = new StringBuilder(); Console.WriteLine(); strBuilder.Append("The properties are:"); foreach (PropertyInfo p ... Read More
The process of injecting (converting) coupled (dependent) objects into decoupled (independent) objects is called Dependency Injection.Types of Dependency InjectionThere are four types of DI −Constructor InjectionSetter InjectionInterface-based injectionService Locator InjectionInterface InjectionInterface Injection is similar to Getter and Setter DI, the Getter, and Setter DI use default getter and setter but Interface Injection uses support interface a kind of explicit getter and setter which sets the interface property.Examplepublic interface IService{ string ServiceMethod(); } public class ClaimService:IService{ public string ServiceMethod(){ return "ClaimService is running"; } } public class AdjudicationService:IService{ public string ServiceMethod(){ ... Read More
The process of injecting (converting) coupled (dependent) objects into decoupled (independent) objects is called Dependency Injection.Types of Dependency InjectionThere are four types of DI −Constructor InjectionSetter InjectionInterface-based injectionService Locator InjectionSetter InjectionGetter and Setter Injection injects the dependency by using default public properties procedure such as Gettter(get(){}) and Setter(set(){}). Examplepublic interface IService{ string ServiceMethod(); } public class ClaimService:IService{ public string ServiceMethod(){ return "ClaimService is running"; } } public class AdjudicationService:IService{ public string ServiceMethod(){ return "AdjudicationService is running"; } } public class BusinessLogicImplementation{ private IService _client; public IService Client{ ... Read More
Software entities like classes, modules and functions should be open for extension but closed for modifications.Definition − The Open Close Principle states that the design and writing of the code should be done in a way that new functionality should be added with minimum changes in the existing code. The design should be done in a way to allow the adding of new functionality as new classes, keeping as much as possible existing code unchanged.ExampleCode Before Open Closed Principleusing System; using System.Net.Mail; namespace SolidPrinciples.Open.Closed.Principle.Before{ public class Rectangle{ public int Width { get; set; } ... Read More
A class should have only one reason to change.Definition − In this context, responsibility is considered to be one reason to change.This principle states that if we have 2 reasons to change for a class, we have to split the functionality in two classes. Each class will handle only one responsibility and if in the future we need to make one change we are going to make it in the class which handles it. When we need to make a change in a class having more responsibilities the change might affect the other functions related to the other responsibility of ... Read More
Use Namespace Newtonsoft.Json.Formatting Newtonsoft.Json.Formatting provides formatting options to Format the JsonNone − No special formatting is applied. This is the default.Indented − Causes child objects to be indented according to the Newtonsoft.Json.JsonTextWriter.Indentation and Newtonsoft.Json.JsonTextWriter.IndentChar settings.Examplestatic void Main(string[] args){ Product product = new Product{ Name = "Apple", Expiry = new DateTime(2008, 12, 28), Price = 3.9900M, Sizes = new[] { "Small", "Medium", "Large" } }; string json = JsonConvert.SerializeObject(product, Formatting.Indented); Console.WriteLine(json); Product deserializedProduct = JsonConvert.DeserializeObject(json); Console.ReadLine(); } class Product{ public String[] Sizes ... Read More