runCommand()
CREATE TABLE IF NOT EXISTS store (id INTEGER UNIQUE PRIMARY KEY AUTOINCREMENT, code TEXT UNIQUE NOT NULL, name TEXT NOT NULL, price TEXT NOT NULL, count INTEGER);
INSERT INTO store ('code', 'name', 'price', 'count') VALUES('6273840263', 'brick', 75, 26);

selectCommand() use when i want one result
SELECT user from users WHERE tag_id = "{stringValue}";

selectCommandList() use when i want multiple results
SELECT * from users WHERE userName = '{stringValue}';
SELECT * from store WHERE code = {intValue};

DbWorker.cs

using Microsoft.Data.Sqlite;
using System;
using System.Collections.Generic;
namespace Herko.RFID
{
	//DbWorker - wrapper for Microsoft.Data.Sqlite;
	//(c) DEJVOSS Productions 2025;
	public class Database
	{
		public SqliteConnection connection = null;
		public Database(String databaseName)
		{
			connection = new SqliteConnection($"Data source={databaseName}");
			connection.Open();
		}
		
		//runs a command without any return value - ex. INSERT, CREATE
		public void runCommand(String commandString)
		{
			if (connection == null)
				throw new Exception("Not connected to a dabase!");
			
			SqliteCommand command = connection.CreateCommand();
			command.CommandText = commandString;
			command.ExecuteNonQuery();
		}

		//runs a command with a return value - ex. SELECT
		public object selectCommand(String commandString)
		{
			if (connection == null)
				throw new Exception("Not connected to a dabase!");

			SqliteCommand command = connection.CreateCommand();
			command.CommandText = commandString;
			return command.ExecuteScalar();
		}

		//returls whole table as a list
		public List selectCommandList(String commandString)
		{
			if (connection == null)
				throw new Exception("Not connected to a dabase!");

			SqliteCommand command = connection.CreateCommand();
			command.CommandText = commandString;
			command.CommandType = System.Data.CommandType.Text;

			SqliteDataReader r = command.ExecuteReader();
			List final = new List();

			while (r.Read())
			{
				String[] oneRow = new String[r.FieldCount];
				for (int i = 0; i < r.FieldCount; i++)
				{
					oneRow[i] = $"{r[i]}";
					//Debug.WriteLine("TEST" + r[i]);
				}
				final.Add(oneRow);
			}
			return final;
		}
	}
}