Lập Trình .NET

Entity Framework Core manages the SqlConnection lifecycle internally, ensuring that connections are opened and closed as needed. Here's a detailed explanation of how this process works:

Opening the Connection

Entity Framework Core opens the connection in a lazy manner, meaning it opens the connection only when it is needed. This typically happens in the following scenarios:

• Query Execution: When a query is executed against the database.
• Save Changes: When changes are saved to the database using context.SaveChanges().
• Explicit Opening: When you explicitly open the connection using context.Database.OpenConnection().

Closing the Connection

Entity Framework Core closes the connection automatically when it is no longer needed. This typically happens in the following scenarios:

• After Query Execution: The connection is closed after the query results are retrieved.
• After Save Changes: The connection is closed after the changes are saved to the database.
• Disposing the DbContext: The connection is closed when the DbContext is disposed, which usually happens at the end of a using block or when the DbContext is explicitly disposed.
• Explicit Closing: When you explicitly close the connection using context.Database.CloseConnection().

Example Code

Here is an example demonstrating how Entity Framework Core manages the connection lifecycle:

Best Practices

• Using using Statement: Always use the using statement to ensure that the DbContext is disposed properly, which in turn ensures that the connection is closed.
• Avoid Explicit Management: Let Entity Framework Core manage the connection lifecycle unless you have a specific reason to manage it manually.

Internals

Internally, Entity Framework Core uses the DbConnection object to manage the connection. Here is a simplified view of what happens:

1. Query Execution:

   • Entity Framework Core checks if the connection is open.
   • If the connection is not open, it opens the connection.
   • Executes the query.
   • Closes the connection if it was opened by Entity Framework Core.

2. Save Changes:

   • Entity Framework Core checks if the connection is open.
   • If the connection is not open, it opens the connection.
   • Saves the changes.
   • Closes the connection if it was opened by Entity Framework Core.

By following these practices and understanding the internals, you can ensure that the SqlConnection is properly managed and closed, preventing potential connection leaks.

    public bool IsAlphanumeric(string input)
    {
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        {
            if (!char.IsLetterOrDigit(c))
            {
                return false;
            }
        }
        return true;
    }

    public bool IsAlphanumeric(string input)
    {
        var regex = new Regex("^[a-zA-Z0-9]*$");
        return regex.IsMatch(input);
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https://learn.microsoft.com/en-us/ef/core/saving/transactions#savepoints

https://github.com/dotnet/efcore/issues/23269

https://stackoverflow.com/questions/65990565/how-to-prevent-ef-core-5-from-creating-a-savepoint-when-saving

https://www.rabbitmq.com/docs/consumers#acknowledgement-timeout

https://stackoverflow.com/questions/42003640/how-to-configure-rabbitmq-config-inside-docker-containers

SELECT 
	DB_NAME(req.database_id) as db_name
	,sqltext.text
    ,req.session_id
    ,req.status
    ,req.command
	,req.start_time
    ,req.cpu_time
    ,req.total_elapsed_time
	,queryplan.query_plan
	,c.client_net_address
	,s.login_name
	,s.login_time
	,s.program_name
	,s.host_name
	,s.host_process_id
	,s.client_interface_name
	,s.client_version
	--,req.*
	--,c.*
	--,s.*
FROM sys.dm_exec_requests req
JOIN sys.dm_exec_connections c on req.connection_id = c.connection_id
JOIN sys.dm_exec_sessions s on req.session_id = s.session_id
CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS sqltext
CROSS APPLY sys.dm_exec_query_plan(req.plan_handle) as queryplan

declare @dateTime datetime2 = SYSDATETIME()
declare @dateTimeOffset datetimeoffset = SYSDATETIMEOFFSET()
 
select @dateTime as [CurrentDateTime],
@dateTimeOffset as [CurrentDateTimeOffset],
CAST(@dateTimeOffset as datetime2) as [DateTime1]


select CAST('2023-04-19 15:32:31.2721255 +07:00' as datetime2) -- Output: 2023-04-19 15:32:31.2721255
select CAST('2023-04-19 15:32:31.2721255 +08:00' as datetime2) -- Output: 2023-04-19 15:32:31.2721255

select SWITCHOFFSET('2023-04-19 15:32:31.2721255 +07:00', '+01:00') -- Output: 2023-04-19 09:32:31.2721255 +01:00
select SWITCHOFFSET('2023-04-19 15:32:31.2721255 +08:00', '+01:00') -- Output: 2023-04-19 08:32:31.2721255 +01:00

select CAST(SWITCHOFFSET('2023-04-19 15:32:31.2721255 +07:00', '+01:00') as datetime2) -- Output: 2023-04-19 09:32:31.2721255
select CAST(SWITCHOFFSET('2023-04-19 15:32:31.2721255 +08:00', '+01:00') as datetime2) -- Output: 2023-04-19 08:32:31.2721255

declare @dateTime datetime2 = SYSDATETIME()
declare @dateTimeOffset datetimeoffset = SYSDATETIMEOFFSET()

select @dateTime as [CurrentDateTime],
@dateTimeOffset as [CurrentDateTimeOffset],
CAST(@dateTime as datetimeoffset) as [DateTimeOffset1],
TODATETIMEOFFSET(@dateTime, '+07:00') as [DateTimeOffset2],
TODATETIMEOFFSET(@dateTime, RIGHT(SYSDATETIMEOFFSET(), 6)) as [DateTimeOffset3]

Using the StringBuilder Class in .NET | Microsoft Docs

Manipulating C# Strings with StringBuilder | CodeGuru.com

https://referencesource.microsoft.com/#mscorlib/system/text/stringbuilder.cs

https://source.dot.net/#System.Private.CoreLib/StringBuilder.cs

https://referencesource.microsoft.com/#mscorlib/system/collections/generic/list.cs

https://source.dot.net/#System.Private.CoreLib/List.cs

C# Collection : Behind the Scene - TAAGUNG

 - Create tls-ssl-settings.reg

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
"SystemDefaultTlsVersions"=dword:00000001
"SchUseStrongCrypto"=dword:00000001

https://docs.microsoft.com/en-us/samples/azure-samples/sftp-creation-template/sftp-on-azure/

https://cloudinfrastructureservices.co.uk/how-to-setup-ftp-server-using-azure-file-share/

https://charbelnemnom.com/how-to-deploy-sftp-service-on-microsoft-azure/

 https://opensource.com/article/21/4/share-files-linux-windows

if(window.navigator && navigator.serviceWorker) {
  navigator.serviceWorker.getRegistrations()
  .then(function(registrations) {
    for(let registration of registrations) {
      registration.unregister();
    }
  });
}

 IIS -> Application Pools -> Advanced Settings -> Load User Profile: True

Import-Module WebAdministration
Set-ItemProperty "IIS:\AppPools\DefaultAppPool" -Name "processModel.loadUserProfile" -Value "True"

https://stackoverflow.com/questions/61467750/identityserver4-windowscryptographicexception-the-system-cannot-find-the-file

https://stackoverflow.com/questions/9951729/x509certificate-constructor-exception

https://github.com/IdentityServer/IdentityServer4/issues/103

https://github.com/IdentityServer/IdentityServer3/issues/2655

Path.GetDirectoryName(Assembly.GetEntryAssembly().Location)

https://stackoverflow.com/questions/10376253/windows-service-get-current-directory

Migrations in Team Environments - EF Core | Microsoft Docs

Code First Migrations in Team Environments - EF6 | Microsoft Docs

Handling EF Core migrations in a team

Overcoming EF Core Migration Conflicts

Recommended way to clean old Entity Framework Core migrations - Stack Overflow

Resetting Entity Framework Migrations to a clean Slate - Rick Strahl's Web Log

Squash migrations · Issue #2174 · dotnet/efcore

cd C:\Program Files\7-Zip

7z a -t7z "D:\Document.7z" "D:\Document"