Interpolated string in C# that string that contains before it symbol $.

That interpolated string can contain special expressions inside in curly braces:

int x = 18;
Console.Write($"Указанный возраст {x} лет."); // Выводит: Указанный возраст 18 лет.

Inside the curly braces can be placed any acceptable expressions C# of any type. C# do transform some value to string, using ToString() method or equivalent for chosen type.

Output format can be changed by add colon and then string format expression, for example:

string s = $"223 in HEX format: {223:X2}"; // X2 - Two digit HEX formatted number.
// Result "223 in HEX format: DF"

Example of converting XML into DYNAMIC and use it.

For begin we need some libraries:

using System;
using System.ComponentModel;
using System.Xml.Linq;
using Newtonsoft.Json;

Code:

string str = "<response><setter><name>Kiril</name></setter></response>";
XDocument doc = XDocument.Parse(str);
string jsn = JsonConvert.SerializeXNode(doc);
dynamic res = JsonConvert.DeserializeObject(jsn);

Console.WriteLine(res.response.setter.name);

That code convert string to XML, then XML to JSON and then convert it to dynamic object.
After that, from dynamic object it get Name property and send it ti console.

Example of creation the SEQUENCE in MSSQL:

CREATE SEQUENCE [dbo].[CardNum] 
 AS [bigint]
 START WITH 1
 INCREMENT BY 1
 MINVALUE -9223372036854775808
 MAXVALUE 9223372036854775807
 CACHE 
GO

That script will create the sequence named CardNum that have type BIGINT and begin from  value 1 in current database.

For turning on xp_cmdshell just do:

-- To allow advanced options to be changed.
EXEC sp_configure 'show advanced options', 1
GO

-- To update the currently configured value for advanced options.
RECONFIGURE
GO

-- To enable the feature.
EXEC sp_configure 'xp_cmdshell', 1
GO

-- To update the currently configured value for this feature.
RECONFIGURE
GO

Restart MSSQL Server on Linux (Ubuntu).

Microsoft is recommend do that like this:

-- Get service state
sudo systemctl status mssql-server

-- Stop service
sudo systemctl stop mssql-server

-- Start service
sudo systemctl start mssql-server

-- Restart service
sudo systemctl restart mssql-server

To get current SESSION ID:

select @@spid

To get current TRANSACTION ID:

select CURRENT_TRANSACTION_ID()

An exemple UPDATE WITH JOIN in MSSQL

update cc
	set cc.ActivateState=2
 from ClientsCards cc
	left join ClientsCardsHeads cch 
 on cch.CardUid=cc.Uid
	where cc.ActivateState=0 and cch.State=3

An "OFFSET FETCH" is a filter, that allows to miss some number of first rows.

For example:

select field1, field2, field3 
from table1
order by field1, field2
offset 100 rows fetch next 50 rows only;

That example return the rows from 101 to 150, from all rows that ordered by field1 and field2.

Two options for executing transaction in MSSQL, each rollback by error.

First option:

BEGIN TRY
    BEGIN TRAN
    UPDATE 1
    UPDATE 2 --Error
    UPDATE 3
    COMMIT TRAN
END TRY
BEGIN CATCH
    ROLLBACK TRAN
END CATCH

An example searching of procedure by text it contain

SELECT name
FROM   sys.procedures
WHERE  Object_definition(object_id) LIKE '%some_text%'

It's return all procedures each contains "some_text"