Hi maddyrafi,
Please refer below links.
For C# tutorials
https://www.tutorialspoint.com/csharp/index.htm
https://tutorialspoint.dev/language/c-sharp
https://www.w3schools.com/cs/index.php
For MySql tutorials
https://www.w3schools.com/mySQl/default.asp
https://www.tutorialspoint.com/mysql/index.htm
https://www.techonthenet.com/mysql/index.php