public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    public ApplicationDbContext() : base("DefaultConnection") { }
}

public class AppUserManager : UserManager<AppUser>{
    public AppUserManager() : base(new UserStore<AppUser>(new ShirazBilitDbContext())) { }
}

public class AppUser : IdentityUser
{
    public string Email { get; set; }
    public string ConfirmationToken { get; set; }
    public bool IsConfirmed { get; set; }
}

  management studio -> select server -> expand Security -> right click Logins ->  select "New Login..."

Right click on db-> properties -> permission -> View Server permission

public class TestController
{
    private readonly ILogger<TestController> _logger;
    public TestController(ILogger<TestController> logger)
    {
        _logger = logger;
    }

   [HttpGet("/")]
    public string Get()
    {
        _logger.LogInformation("hello world");
          return "Hello world!";
    }
}

CA1848: For improved performance, use the LoggerMessage delegates instead of calling LogInformation

public record Person (int Id, string Name);

var person = new Person(123, "Test");

_logger.LogInformation("hello to {Person}", person);

info: TestController[0]
hello world to Person { Id = 123, Name = Test }

_logger.LogInformation($"hello world to {person}"); // Using interpolation instead of structured logging

if (_logger.IsEnabled(LogLevel.Information))
{
   _logger.LogInformation("hello world to {Person}", person);
}

_logger.LogInformation("hello world to {Person} because {Reason}", person);

private static readonly Action<ILogger, Person, Exception?> _logHelloWorld =
    LoggerMessage.Define<Person>(
        logLevel: LogLevel.Information,
        eventId: 0,
        formatString: "hello world to {Person}");

[HttpGet("/")]
public string Get()
{
    var person = new Person(123, "Test");
    _logHelloWorld(_logger, person, null);
      return "Hello world!";
}

public partial class TestController
{
   [LoggerMessage(0, LogLevel.Information, "hello world to {Person}")]
   partial void LogHelloWorld(Person person);
}

[LoggerMessage(0, LogLevel.Information, "hello world to {Person} with a {Reason}")]
partial void LogHelloWorld(Person person);

[LoggerMessage(Message = "hello world to {Person}")]
partial void LogHelloWorld(LogLevel logLevel, Person person);

• SQL Server Database Engine از کلمه کلیدی SPARSE برای تعریف یک ستون که مقادیر آن می‌بایست بهینه شود استفاده می‌نماید.
• نمای Catalog  جداول با ستون sparse شبیه جداول معمولی می‌باشد.
• مقدار برگشتی از تابع COLUMNS_UPDATED با ستون sparce متفاوت از ستون معمولی است.

• sparse column می‌ بایست nullable باشد و نمی‌تواند ROWGUIDCOL یا IDENTITY باشد. 
• sparse column مقدار پیش فرض نمی‌تواند داشته باشد 
• ستون محاسبه ای نمی‌تواند sparse باشد
• sparse column نمی‌تواند بخشی از clustered index یا  unique primary key index باشد
• sparse column  نمی تواند بخشی از  user-defined table باشد

sp_spaceused 'Employees'
GO
sp_spaceused 'Employees_sparse' 

using System.Collections.Generic;
using System.Runtime.CompilerServices;

namespace ConditionalWeakTableSamples
{
    public static class AttachedProperties
    {
        public static ConditionalWeakTable<object,
            Dictionary<string, object>> ObjectCache = new ConditionalWeakTable<object,
                Dictionary<string, object>>();

        public static void SetValue<T>(this T obj, string name, object value) where T : class
        {
            var properties = ObjectCache.GetOrCreateValue(obj);

            if (properties.ContainsKey(name))
                properties[name] = value;
            else
                properties.Add(name, value);
        }

        public static T GetValue<T>(this object obj, string name)
        {
            Dictionary<string, object> properties;
            if (ObjectCache.TryGetValue(obj, out properties) && properties.ContainsKey(name))
                return (T)properties[name];
            return default(T);
        }

        public static object GetValue(this object obj, string name)
        {
            return obj.GetValue<object>(name);
        }
    }
}

    public static class ISecurityPrincipalExtension
    {
        public static bool Disclaimer(this IPrincipal principal)
        {
            return principal.GetValue<bool>("Disclaimer");
        }

        public static void SetDisclaimer(this IPrincipal principal, bool value)
        {
            principal.SetValue("Disclaimer", value);
        }
    }

using System.Runtime.CompilerServices;

namespace ConditionalWeakTableSamples
{
    public static class PropertyExtensions
    {
        private class ExtraPropertyHolder
        {
            public bool IsDirty { get; set; }
        }

        private static readonly ConditionalWeakTable<object, ExtraPropertyHolder> _isDirtyTable
                = new ConditionalWeakTable<object, ExtraPropertyHolder>();

        public static bool IsDirty(this object @this)
        {
            return _isDirtyTable.GetOrCreateValue(@this).IsDirty;
        }

        public static void SetIsDirty(this object @this, bool isDirty)
        {
            _isDirtyTable.GetOrCreateValue(@this).IsDirty = isDirty;
        }
    }
}

public void Closed(DbConnection connection, DbConnectionInterceptionContext interceptionContext)
{
}

using System;
using System.Runtime.CompilerServices;

namespace ConditionalWeakTableSamples
{
    public static class UniqueIdExtensions
    {
        static readonly ConditionalWeakTable<object, string> _idTable = 
                                    new ConditionalWeakTable<object, string>();

        public static string GetUniqueId(this object obj)
        {
            return _idTable.GetValue(obj, o => Guid.NewGuid().ToString());
        }

        public static string GetUniqueId(this object obj, string key)
        {
            return _idTable.GetValue(obj, o => key);
        }
    }
}