1. استفاده از جداول جدا برای هر کدام از جداول به صورتیکه یک ارتباط یک به چند مابین آنها برقرار است. از این جداول تحت عنوان HistoryTable یاد می‌شود.
2. استفاده از یک جدول برای نگهداری تاریخچه‌ی تغییرات جداولی که نیازمند این امکان هستند. 

  C: \ Users \ YOUR_USERNAME \ Documents \ IISExpress \ config / applicationhost.config

  “Unable to create the virtual directory. You must use specify ‘localhost’ for the server name”

 " Invalid URL:the hostame could not be parsed "

public class row
{
        public int Id { get; set; }
        public string username{ get; set; }
        public string ip{ get; set; }
        .
        .
        public virtual Field Field { get; set; }
        public int fieldId { get; set; }
}

/// <summary>
    /// 
    /// </summary>
    public static class FullTextPrefixes
    {
        /// <summary>
        /// 
        /// </summary>
        public const string ContainsPrefix = "-CONTAINS-";

        /// <summary>
        /// 
        /// </summary>
        public const string FreetextPrefix = "-FREETEXT-";

        /// <summary>
        /// 
        /// </summary>
        /// <param name="searchTerm"></param>
        /// <returns></returns>
        public static string Contains(string searchTerm)
        {
            return string.Format("({0}{1})", ContainsPrefix, searchTerm);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="searchTerm"></param>
        /// <returns></returns>
        public static string Freetext(string searchTerm)
        {
            return string.Format("({0}{1})", FreetextPrefix, searchTerm);
        }

    }

public static class FullTextSearchExtensions
    {

        /// <summary>
        /// 
        /// </summary>
        /// <typeparam name="TEntity"></typeparam>
        /// <param name="source"></param>
        /// <param name="expression"></param>
        /// <param name="searchTerm"></param>
        /// <returns></returns>
        public static IQueryable<TEntity> FreeTextSearch<TEntity>(this IQueryable<TEntity> source, Expression<Func<TEntity, object>> expression, string searchTerm) where TEntity : class
        {
            return FreeTextSearchImp(source, expression, FullTextPrefixes.Freetext(searchTerm));
        }

        /// <summary>
        /// 
        /// </summary>
        /// <typeparam name="TEntity"></typeparam>
        /// <param name="source"></param>
        /// <param name="expression"></param>
        /// <param name="searchTerm"></param>
        /// <returns></returns>
        public static IQueryable<TEntity> ContainsSearch<TEntity>(this IQueryable<TEntity> source, Expression<Func<TEntity, object>> expression, string searchTerm) where TEntity : class
        {
            return FreeTextSearchImp(source, expression, FullTextPrefixes.Contains(searchTerm));
        }

        /// <summary>
        /// 
        /// </summary>
        /// <typeparam name="TEntity"></typeparam>
        /// <param name="source"></param>
        /// <param name="expression"></param>
        /// <param name="searchTerm"></param>
        /// <returns></returns>
        private static IQueryable<TEntity> FreeTextSearchImp<TEntity>(this IQueryable<TEntity> source, Expression<Func<TEntity, object>> expression, string searchTerm)
        {
            if (String.IsNullOrEmpty(searchTerm))
            {
                return source;
            }

            // The below represents the following lamda:
            // source.Where(x => x.[property].Contains(searchTerm))

            //Create expression to represent x.[property].Contains(searchTerm)
            //var searchTermExpression = Expression.Constant(searchTerm);
            var searchTermExpression = Expression.Property(Expression.Constant(new { Value = searchTerm }), "Value");
            var checkContainsExpression = Expression.Call(expression.Body, typeof(string).GetMethod("Contains"), searchTermExpression);

            //Join not null and contains expressions

            var methodCallExpression = Expression.Call(typeof(Queryable),
                                                       "Where",
                                                       new[] { source.ElementType },
                                                       source.Expression,
                                                       Expression.Lambda<Func<TEntity, bool>>(checkContainsExpression, expression.Parameters));

            return source.Provider.CreateQuery<TEntity>(methodCallExpression);
        }

 public class FtsInterceptor : IDbCommandInterceptor
    {

        /// <summary>
        /// 
        /// </summary>
        /// <param name="command"></param>
        /// <param name="interceptionContext"></param>
        public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
        {
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="command"></param>
        /// <param name="interceptionContext"></param>
        public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
        {
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="command"></param>
        /// <param name="interceptionContext"></param>
        public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
        {
            RewriteFullTextQuery(command);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="command"></param>
        /// <param name="interceptionContext"></param>
        public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
        {
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="command"></param>
        /// <param name="interceptionContext"></param>
        public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
        {
            RewriteFullTextQuery(command);
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="command"></param>
        /// <param name="interceptionContext"></param>
        public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
        {
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="cmd"></param>
        public static void RewriteFullTextQuery(DbCommand cmd)
        {
            var text = cmd.CommandText;
            for (var i = 0; i < cmd.Parameters.Count; i++)
            {
                var parameter = cmd.Parameters[i];
                if (
                    !parameter.DbType.In(DbType.String, DbType.AnsiString, DbType.StringFixedLength,
                        DbType.AnsiStringFixedLength)) continue;
                if (parameter.Value == DBNull.Value)
                    continue;
                var value = (string)parameter.Value;
                if (value.IndexOf(FullTextPrefixes.ContainsPrefix, StringComparison.Ordinal) >= 0)
                {
                    parameter.Size = 4096;
                    parameter.DbType = DbType.AnsiStringFixedLength;
                    value = value.Replace(FullTextPrefixes.ContainsPrefix, ""); // remove prefix we added n linq query
                    value = value.Substring(1, value.Length - 2); // remove %% escaping by linq translator from string.Contains to sql LIKE
                    parameter.Value = value;
                    cmd.CommandText = Regex.Replace(text,
                        string.Format(
                            @"\[(\w*)\].\[(\w*)\]\s*LIKE\s*@{0}\s?(?:ESCAPE N?'~')", parameter.ParameterName),
                        string.Format(@"CONTAINS([$1].[$2], @{0})", parameter.ParameterName));
                    if (text == cmd.CommandText)
                        throw new Exception("FTS was not replaced on: " + text);
                    text = cmd.CommandText;
                }
                else if (value.IndexOf(FullTextPrefixes.FreetextPrefix, StringComparison.Ordinal) >= 0)
                {
                    parameter.Size = 4096;
                    parameter.DbType = DbType.AnsiStringFixedLength;
                    value = value.Replace(FullTextPrefixes.FreetextPrefix, ""); // remove prefix we added n linq query
                    value = value.Substring(1, value.Length - 2); // remove %% escaping by linq translator from string.Contains to sql LIKE
                    parameter.Value = value;
                    cmd.CommandText = Regex.Replace(text,
                        string.Format(
                            @"\[(\w*)\].\[(\w*)\]\s*LIKE\s*@{0}\s?(?:ESCAPE N?'~')", parameter.ParameterName),
                        string.Format(@"FREETEXT([$1].[$2], @{0})", parameter.ParameterName));
                    if (text == cmd.CommandText)
                        throw new Exception("FTS was not replaced on: " + text);
                    text = cmd.CommandText;
                }
            }
        }

    }

public class Note
    {
        /// <summary>
        /// 
        /// </summary>
        public int Id { get; set; }

        /// <summary>
        /// 
        /// </summary>
        public string NoteText { get; set; }
    }

  public class FtsSampleContext : DbContext
    {
        /// <summary>
        /// 
        /// </summary>
        public DbSet<Note> Notes { get; set; }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="modelBuilder"></param>
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Configurations.Add(new NoteMap());
        }
    }

/// <summary>
    /// 
    /// </summary>
    class Program
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="args"></param>
        static void Main(string[] args)
        {
            DbInterception.Add(new FtsInterceptor());
            const string searchTerm = "john";
            using (var db = new FtsSampleContext())
            {
                var result1 = db.Notes.FreeTextSearch(a => a.NoteText, searchTerm).ToList();
                //SQL Server Profiler result ===>>>
                //exec sp_executesql N'SELECT 
                //    [Extent1].[Id] AS [Id], 
                //    [Extent1].[NoteText] AS [NoteText]
                //    FROM [dbo].[Notes] AS [Extent1]
                //    WHERE FREETEXT([Extent1].[NoteText], @p__linq__0)',N'@p__linq__0 
                //char(4096)',@p__linq__0='(john)'
                var result2 = db.Notes.ContainsSearch(a => a.NoteText, searchTerm).ToList();
                //SQL Server Profiler result ===>>>
                //exec sp_executesql N'SELECT 
                //    [Extent1].[Id] AS [Id], 
                //    [Extent1].[NoteText] AS [NoteText]
                //    FROM [dbo].[Notes] AS [Extent1]
                //    WHERE CONTAINS([Extent1].[NoteText], @p__linq__0)',N'@p__linq__0 
                //char(4096)',@p__linq__0='(john)'
            }
            Console.ReadKey();
        }
    }

CREATE FUNCTION dbo.checkPerson(@data XML)
RETURNS BIT WITH SCHEMABINDING AS
BEGIN
   RETURN @data.exist('/people/person')
END
GO

CREATE TABLE tblXML
(
id INT PRIMARY KEY,
doc XML CHECK(dbo.checkPerson(doc)=1)  
)
GO

 INSERT INTO tblXML (id,  doc) VALUES
(
 1, '<people><person name="Vahid"/></people>'
)

INSERT INTO tblXML (id,  doc) VALUES
(
 2, '<people><emp name="Vahid"/></people>'
)

 The INSERT statement conflicted with the CHECK constraint "CK__tblXML__doc__060DEAE8".
The conflict occurred in database "testdb", table "dbo.tblXML", column 'doc'.
The statement has been terminated.

 CREATE TABLE xml_tab
(
 id INT IDENTITY PRIMARY KEY,
 xml_col  XML
)

 INSERT INTO xml_tab
VALUES ('<people><person name="Vahid"/></people>')
INSERT INTO xml_tab
VALUES ('<people><person name="Farid"/></people>')

 CREATE FUNCTION getIdValue(@doc XML)
RETURNS int WITH SCHEMABINDING AS
BEGIN
  RETURN @doc.value('/*[1]/@Id', 'int')
END

 CREATE TABLE docs_tab
(
id INT PRIMARY KEY,
doc XML,
CONSTRAINT id_chk CHECK(dbo.getIdValue(doc)=id)  
)

 INSERT INTO docs_tab (id,  doc) VALUES
(
 1, '<Invoice Id="1"/>'
)

INSERT INTO docs_tab (id,  doc) VALUES
(
 2, '<Invoice Id="1"/>'
)

 The INSERT statement conflicted with the CHECK constraint "id_chk".
The conflict occurred in database "testdb", table "dbo.docs_tab".
The statement has been terminated.

 CREATE TABLE Invoices
(
 doc XML,
 id AS dbo.getIdValue(doc) PERSISTED PRIMARY KEY
)

 INSERT INTO Invoices VALUES
(
 '<Invoice Id="1"/>'
)
INSERT INTO Invoices VALUES
(
 '<Invoice Id="1"/>'
)

 Violation of PRIMARY KEY constraint 'PK__Invoices__3213E83F145C0A3F'.
Cannot insert duplicate key in object 'dbo.Invoices'. The duplicate key value is (1).
The statement has been terminated.

 DECLARE @doc XML
SET @doc = '<foo bar="baz" />'
SELECT @doc.query('/foo/@bar')

 XQuery [query()]: Attribute may not appear outside of an element

 DECLARE @doc XML
SET @doc = '<foo bar="baz" />'
SELECT @doc.query('data(/foo/@bar)')

 DECLARE @x XML
SET @x = '<x>hello<y>world</y></x><x>again</x>'
SELECT @x.query('data(/*)')

 DECLARE @x XML
SET @x = '<x>hello<y>world</y></x><x>again</x>'
SELECT @x.query('string(/*)')

 XQuery [query()]: 'string()' requires a singleton (or empty sequence), found operand of type 'element(*,xdt:untyped) *'

 SELECT @x.query('string(/*[1])')

 SELECT @x.query('string(/)')

 DECLARE @x XML = '<age>12</age>'
SELECT @x.query('string(/age[1])')

 CREATE XML SCHEMA COLLECTION root_el AS
'<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
                  targetNamespace="urn:geo">
      <xs:element name="Root" type="xs:string" />    
</xs:schema>
'
GO

 DECLARE @xmlDoc XML
SET @xmlDoc = '<g:Root xmlns:g="urn:geo">datadata...</g:Root>'
SELECT @xmlDoc.query('
declare namespace g="urn:geo";
/g:Root/text()
')

 DECLARE @xmlDoc XML(root_el)
SET @xmlDoc = '<g:Root xmlns:g="urn:geo">datadata...</g:Root>'
SELECT @xmlDoc.query('
declare namespace g="urn:geo";
/g:Root[1]/text()
')

 XQuery [query()]: 'text()' is not supported on simple typed or 'http://www.w3.org/2001/XMLSchema#anyType'
elements, found 'element(g{urn:geo}:Root,xs:string) *'.

 DECLARE @xmlDoc XML(root_el)
SET @xmlDoc = '<g:Root xmlns:g="urn:geo">datadata...</g:Root>'
SELECT @xmlDoc.query('
declare namespace g="urn:geo";
data(/g:Root[1])
')

data(/age/text())

<input dir="ltr" class="form-control input-validation-error" 
type="email" 
data-val="true" 
data-val-email="'آدرس ایمیل' is not a valid email address." 
data-val-remote="این آدرس ایمیل هم اکنون مورد استفاده‌است" 
data-val-remote-url="/Home/ValidateUniqueEmail" 
data-val-required="'آدرس ایمیل' must not be empty." 
id="Email" 
name="Email" 
>

using System.ComponentModel.DataAnnotations;

namespace FluentValidationSample.Models
{
    public class UserModel
    {
        [Display(Name = "نام کاربری")]
        public string Username { get; set; }

        [Display(Name = "سن")]
        public int Age { get; set; }

        [Display(Name = "سابقه کار")]
        public int Experience { get; set; }

        [DataType(DataType.EmailAddress)]
        [Display(Name = "آدرس ایمیل")]
        public string Email { get; set; }
    }
}

using System.Linq;

namespace FluentValidationSample.Services
{
    public interface IUsersService
    {
        bool IsUniqueEmail(string emailAddress);
    }

    public class UsersService : IUsersService
    {
        public bool IsUniqueEmail(string emailAddress)
        {
            string[] registedEmails = {
                "email@site.com",
                "test@gmail.com"
            };
            return !registedEmails.Contains(emailAddress);
        }
    }
}

namespace FluentValidationSample.Web
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddScoped<IUsersService, UsersService>();

using FluentValidation.Validators;
using FluentValidationSample.Services;

namespace FluentValidationSample.ModelsValidations
{
    public class UniqueEmailValidator : PropertyValidator
    {
        private readonly IUsersService _usersService;

        public UniqueEmailValidator(IUsersService usersService)
                : base("این آدرس ایمیل هم اکنون مورد استفاده‌است")
        {
            _usersService = usersService;
        }

        protected override bool IsValid(PropertyValidatorContext context)
        {
            return context.PropertyValue != null &&
                    _usersService.IsUniqueEmail((string)context.PropertyValue);
        }
    }
}

using FluentValidation;
using FluentValidationSample.Services;

namespace FluentValidationSample.ModelsValidations
{
    public static class CustomValidatorExtensions
    {
        public static IRuleBuilderOptions<T, string> UniqueEmail<T>(
            this IRuleBuilder<T, string> ruleBuilder, IUsersService usersService)
        {
            return ruleBuilder.SetValidator(new UniqueEmailValidator(usersService));
        }
    }
}

using FluentValidation;
using FluentValidationSample.Models;
using FluentValidationSample.Services;

namespace FluentValidationSample.ModelsValidations
{
    public class UserModelValidator : AbstractValidator<UserModel>
    {
        public UserModelValidator(IUsersService usersService)
        {
            RuleFor(x => x.Username).NotNull();
            RuleFor(x => x.Age).NotNull();
            RuleFor(x => x.Experience).LowerThan(nameof(UserModel.Age)).NotNull();
            RuleFor(x => x.Email).EmailAddress().NotNull().UniqueEmail(usersService);
        }
    }
}

using FluentValidation;
using FluentValidation.AspNetCore;
using FluentValidation.Internal;
using FluentValidation.Resources;
using FluentValidation.Validators;
using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;

namespace FluentValidationSample.ModelsValidations
{
    public class RemoteClientValidator : ClientValidatorBase
    {
        public string RemoteUrl { set; get; }

        public RemoteClientValidator(PropertyRule rule, IPropertyValidator validator) :
            base(rule, validator)
        {
        }

        public override void AddValidation(ClientModelValidationContext context)
        {
            MergeAttribute(context.Attributes, "data-val", "true");
            MergeAttribute(context.Attributes, "data-val-remote", GetErrorMessage(context));
            MergeAttribute(context.Attributes, "data-val-remote-url", RemoteUrl);
        }

        private string GetErrorMessage(ClientModelValidationContext context)
        {
            var formatter = ValidatorOptions.MessageFormatterFactory().AppendPropertyName(Rule.GetDisplayName());
            string messageTemplate;
            try
            {
                messageTemplate = Validator.Options.ErrorMessageSource.GetString(null);
            }
            catch (FluentValidationMessageFormatException)
            {
                messageTemplate = ValidatorOptions.LanguageManager.GetStringForValidator<NotEmptyValidator>();
            }
            return formatter.BuildMessage(messageTemplate);
        }
    }
}

<input dir="ltr" class="form-control input-validation-error" 
type="email" 
data-val="true" 
data-val-email="'آدرس ایمیل' is not a valid email address." 
data-val-remote="این آدرس ایمیل هم اکنون مورد استفاده‌است" 
data-val-remote-url="/Home/ValidateUniqueEmail" 
data-val-required="'آدرس ایمیل' must not be empty." 
id="Email" 
name="Email" 
>

namespace FluentValidationSample.Web
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddScoped<IUsersService, UsersService>();

            services.AddControllersWithViews().AddFluentValidation(
                fv =>
                {
                    fv.RegisterValidatorsFromAssembly(Assembly.GetExecutingAssembly());
                    fv.RegisterValidatorsFromAssemblyContaining<RegisterModelValidator>();
                    fv.RunDefaultMvcValidationAfterFluentValidationExecutes = false;

                    fv.ConfigureClientsideValidation(clientSideValidation =>
                    {
                        // ...

                        clientSideValidation.Add(
                            validatorType: typeof(UniqueEmailValidator),
                            factory: (context, rule, validator) =>
                                        new RemoteClientValidator(rule, validator)
                                        {
                                            RemoteUrl = "/Home/ValidateUniqueEmail"
                                        });
                    });
                }
            );
        }

namespace FluentValidationSample.Web.Controllers
{
    public class HomeController : Controller
    {
        private readonly IUsersService _usersService;

        public HomeController(IUsersService usersService)
        {
            _usersService = usersService;
        }

         // ...

        public IActionResult ValidateUniqueEmail(string email)
        {
            return Ok(_usersService.IsUniqueEmail(email));
        }
    }
}

<script src="~/lib/jquery/dist/jquery.min.js"></script>
<script src="~/lib/bootstrap/dist/js/bootstrap.bundle.min.js"></script>
<script src="~/lib/jquery-validation/dist/jquery.validate.js"></script>
<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>
<script src="~/js/site.js" asp-append-version="true"></script>

 public class LogRequestHandler : IHttpHandler

using System;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using System.Web;

namespace Async14
{
    public class LogRequestHandler : HttpTaskAsyncHandler
    {
        public override async Task ProcessRequestAsync(HttpContext context)
        {
            string url = context.Request.QueryString["rssfeedURL"];
            if (string.IsNullOrWhiteSpace(url))
            {
                context.Response.Write("Rss feed URL is not provided");
            }

            using (var webClient = new WebClient {Encoding = Encoding.UTF8})
            {
                webClient.Headers.Add("User-Agent", "LogRequestHandler 1.0");
                var rssfeed = await webClient.DownloadStringTaskAsync(url);
                context.Response.Write(rssfeed);
            }
        }

        public override bool IsReusable
        {
            get { return true; }
        }

        public override void ProcessRequest(HttpContext context)
        {
            throw new Exception("The ProcessRequest method has no implementation.");
        }
    }
}

 http://localhost:4207/LogRequestHandler.ashx?rssfeedURL=https://www.dntips.ir/feed/latestchanges

using System;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using System.Web.UI;

namespace Async14
{
    public partial class _default : Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            RegisterAsyncTask(new PageAsyncTask(LoadSomeData));
        }

        public async Task LoadSomeData()
        {
            using (var webClient = new WebClient { Encoding = Encoding.UTF8 })
            {
                webClient.Headers.Add("User-Agent", "LogRequest 1.0");
                var rssfeed = await webClient.DownloadStringTaskAsync("url");

                //listcontacts.DataSource = rssfeed;
            }
        }
    }
}

 <%@ Page Language="C#" AutoEventWireup="true"
Async="true"
  CodeBehind="default.aspx.cs" Inherits="Async14._default" %>