Error CS1579 foreach statement cannot operate on variables of type ‘IEnumerator’
because ‘IEnumerator’ does not contain a public instance or extension definition for ‘GetEnumerator’

static class Extensions
{
   public static IEnumerator<T> GetEnumerator<T>(this IEnumerator<T> enumerator) => enumerator;
}

class Program
{
    void Main()
    {
        var enumerator = Enumerable.Range(0, 10).GetEnumerator();
        foreach (var item in enumerator)
        {
            Console.WriteLine(item);
        }
    }
}

static class Extensions
{
    public static IAsyncEnumerator<T> GetAsyncEnumerator<T>(this IAsyncEnumerator<T> enumerator) => enumerator;
}

class Program
{
    static async Task Main()
    {
        var enumerator = GetAsyncEnumerator();
        await foreach (var item in enumerator)
        {
            Console.WriteLine(item);
        }
    }

    static async IAsyncEnumerator<int> GetAsyncEnumerator()
    {
        yield return 0;
        await Task.Delay(1);
        yield return 1;
    }
}

class Program
{
    static void Main()
    {
        foreach (var item in (1, 2, 3))
        {
            Console.WriteLine(item);
        }
    }
}

foreach statement cannot operate on variables of type '(int, int, int)'
because '(int, int, int)' does not contain a public instance or extension definition
for 'GetEnumerator' [CS9Features]csharp(CS1579)

static class Extensions
{
    public static IEnumerator<object> GetEnumerator<T1, T2, T3>(this ValueTuple<T1, T2, T3> tuple)
    {
        yield return tuple.Item1;
        yield return tuple.Item2;
    }
}

  <system.webServer>

    <httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files">
      <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" />
      <dynamicTypes>
        <add mimeType="text/*" enabled="true" />
        <add mimeType="message/*" enabled="true" />
        <add mimeType="application/x-javascript" enabled="true" />
        <add mimeType="application/javascript" enabled="true" />
        <add mimeType="application/json" enabled="true" />
        <add mimeType="application/json; charset=utf-8" enabled="true" />
        <add mimeType="application/atom+xml" enabled="true" />
        <add mimeType="application/xaml+xml" enabled="true" />
        <add mimeType="*/*" enabled="false" />
      </dynamicTypes>
      <staticTypes>
        <add mimeType="text/*" enabled="true" />
        <add mimeType="message/*" enabled="true" />
        <add mimeType="application/x-javascript" enabled="true" />
        <add mimeType="application/javascript" enabled="true" />
        <add mimeType="application/json" enabled="true" />
        <add mimeType="application/json; charset=utf-8" enabled="true" />
        <add mimeType="application/atom+xml" enabled="true" />
        <add mimeType="application/xaml+xml" enabled="true" />
        <add mimeType="*/*" enabled="false" />
      </staticTypes>
    </httpCompression>
    <urlCompression doStaticCompression="true" doDynamicCompression="true" />

  </system.webServer>

<system.webServer>
   <serverRuntime frequentHitThreshold="1" frequentHitTimePeriod="10:00:00" />
</system.webServer>

 C:\Windows\System32\inetsrv\appcmd.exe unlock config /section:system.webServer/serverRuntime

 <httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files" minFileSizeForComp="1024">

create trigger Prevent_AlterDrop
on database
for drop_table, alter_table
as
  print 'table can not be dropped or altered'
  rollback transaction

  CREATE TABLE ddl_log 
  (
     EventType nvarchar(100), 
 PostTime datetime,
 SPID nvarchar(100),
 ServerName nvarchar(100),
 LoginName nvarchar(100),
 UserName  nvarchar(100),
 DatabaseName  nvarchar(100),
 ObjectName  nvarchar(100),
 ObjectType  nvarchar(100),
 DefaultSchema nvarchar(100),
 [SID]  nvarchar(100),
 TSQLCommand nvarchar(2000));

CREATE TRIGGER [Log] ON DATABASE
 FOR DDL_DATABASE_LEVEL_EVENTS
 AS
 DECLARE @data XML
 SET @data = EVENTDATA()
 INSERT INTO ddl_log
 VALUES (
   @data.value('(/EVENT_INSTANCE/EventType)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/PostTime)[1]',   'datetime'),
   @data.value('(/EVENT_INSTANCE/SPID)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/ServerName)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/LoginName)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/UserName)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/DatabaseName)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/ObjectName)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/ObjectType)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/DefaultSchema)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/SID)[1]',   'nvarchar(100)'),
   @data.value('(/EVENT_INSTANCE/TSQLCommand)[1]',   'nvarchar(2000)'));

Server Level

DDL_SERVER_LEVEL_EVENTS

 DDL_LINKED_SERVER_EVENTS

 DDL_LINKED_SERVER_LOGIN_EVENTS

 DDL_REMOTE_SERVER_EVENTS

 DDL_EXTENDED_PROCEDURE_EVENTS

 DDL_MESSAGE_EVENTS

 DDL_ENDPOINT_EVENTS

 DDL_SERVER_SECURITY_EVENTS

 DDL_LOGIN_EVENTS

 DDL_GDR_SERVER_EVENTS

 DDL_AUTHORIZATION_SERVER_EVENT Database Level

Database Level

DDL_TABLE_VIEW_EVENTS

DDL_TABLE-EVENTS

DDL_VIEW_EVENTS

DDL_INDEX_EVENTS

DDL_STATISTICS_EVENTS

DDL_DATABASE_SECURITY_EVENTS

DDL_CERTIFICATE_EVENTS

DDL_USER_EVENTS

DDL_ROLE_EVENTS

DDL_APPLICATION_ROLE_EVENTS

DDL_SCHEMA_EVENTS

DDL_GDR_DATABASE_EVENTS

DDL_AUTHORIZATION_DATABASE_EVENTS

DDL_FUNCTION_EVENTS

DDL_PROCEDUER_EVENTS

DDL_TRIGGER_EVENTS

DDL_PARTITION_EVENTS

DDL_PARTITION_FUNCTION_EVENTS

DDL_PARTITION_SCHEME_EVENTS

DDL_SSB_EVENTS

DDL_MESSAGE_TYPE_EVENTS

DDL_CONTRACT_EVENTS

DDL_QUEUE_EVENTS

DDL_SERVER_EVENTS

DDL_ROUTE_EVENTS

DDL_REMOTE_SERVICE_BINDING_EVENTS

DDL_XML_SCHEMA_COLEECTION_EVENTS

DDL_FULLTEXT_CATALOG_EVENTS

DDL_DEFAULT_EVENTS

DDL_EXTENDED_PROPERTY_EVENTS

DDL_PLAN_GUIDE_EVENTS

DDL_RULE_EVENTS

DDL_SYNONYM_EVENTS

DDL_EVENT_NOTIFICATION_EVENTS

DDL_ASSEMBLY_EVENTS

DDL_TYPE_EVENTS

D:\Program Files\MongoDB\Server\3.4\bin>mongoexport -d publisher -c books -f Title,ISBN --csv -o D:\temp\books.csv
2017-03-04T22:50:20.671+0330    csv flag is deprecated; please use --type=csv instead
2017-03-04T22:50:20.673+0330    connected to: localhost
2017-03-04T22:50:20.673+0330    exported 7 records

D:\Program Files\MongoDB\Server\3.4\bin>mongoimport -d publisher -c books -f Title,ISBN --type csv D:\temp\books.csv
2017-03-04T23:05:50.588+0330    connected to: localhost
2017-03-04T23:05:50.591+0330    imported 8 documents

Asynchronous Main (it is going to be released in version 7.1)
Default Literal (it is going to be released in version 7.1)
Readonly ref (it is going to be released in version 7.2)
Default interface methods (it is going to be released in version 8.0)
Optional tuple names (to be released in 7.1)