IDatabase.cs

    class IDatabase
    {
        public DataTable ReadTable(SQLiteConnection Connection, string TableName)
        {
            List<string> Data = new List<string>();
            string Command = $"SELECT * FROM {TableName}";
            SQLiteCommand SqliteCommand = new SQLiteCommand(Command, Connection);
            SQLiteDataAdapter da = new SQLiteDataAdapter(SqliteCommand);
            DataTable dt = new DataTable();
            da.Fill(dt);
            return dt;
        }

        public SQLiteConnection ConnectToDatabase(string FullPath)
        {
            SQLiteConnection Connection = new SQLiteConnection("Data Source=" + FullPath + ";Version=3;");
            Connection = Connection.OpenAndReturn();
            return Connection;
        }

        public int SendCommand(SQLiteConnection Connection, string Command)
        {
            SQLiteCommand SqliteCommand = new SQLiteCommand(Command, Connection);
            return SqliteCommand.ExecuteNonQuery();
        }

        public bool DataExists(SQLiteConnection Connection, string TableName, string ColumnName, string Value)
        {
            string Command = "SELECT count(*) FROM " + TableName + " WHERE word=" + Value;
            SQLiteCommand SqliteCommand = new SQLiteCommand(Command, Connection);
            object Result = SqliteCommand.ExecuteScalar();
            if (Result == null)
                return false;
            else
                return true;
        }

        public List<string> ReadData(SQLiteConnection Connection, string Selection, string TableName, string Field)
        {
            List<string> Data = new List<string>();
            string Command = $"SELECT {Selection} FROM {TableName}";
            SQLiteCommand SqliteCommand = new SQLiteCommand(Command, Connection);
            var Reader = SqliteCommand.ExecuteReader();
            while (Reader.Read())
            {
                Data.Add(Reader[Field].ToString());
            }
            return Data;
        }

        public List<KeyValuePair<string, string>> ReadDataJoinedKVP(SQLiteConnection Connection, string Selection, string TableName, string Field_1, string Field_2)
        {
            var Data = new List<KeyValuePair<string, string>>();
            string Command = $"SELECT {Selection} FROM {TableName}";
            SQLiteCommand SqliteCommand = new SQLiteCommand(Command, Connection);
            var Reader = SqliteCommand.ExecuteReader();
            while (Reader.Read())
            {
                Data.Add(new KeyValuePair<string, string>(Reader[Field_1].ToString(), Reader[Field_2].ToString()));
            }
            return Data;
        }

        public List<string> ReadDataJoined(SQLiteConnection Connection, string Selection, string TableName, string Field_1, string Field_2)
        {
            var Data = new List<string>();
            string Command = $"SELECT {Selection} FROM {TableName}";
            SQLiteCommand SqliteCommand = new SQLiteCommand(Command, Connection);
            var Reader = SqliteCommand.ExecuteReader();
            while (Reader.Read())
            {
                Data.Add($"{Reader[Field_1].ToString()} {Reader[Field_2].ToString()}");
            }
            return Data;
        }

        public int InsertData(SQLiteConnection Connection, string TableName, string ColumnNames, string Values)
        {

            Values = Values.Replace(", ", ",");
            string[] ValueArray = Values.Split(',');
            Values = "";
            for (int i = 0; i <= ValueArray.Length - 1; i++)
            {
                int IntValue = 0;
                if (int.TryParse(ValueArray[i], out IntValue) == false)
                {
                    if (i != ValueArray.Length - 1)
                        Values += "\"" + ValueArray[i] + "\", ";
                    else
                        Values += "\"" + ValueArray[i] + "\"";
                }
                else
                {
                    if (i != ValueArray.Length - 1)
                        Values += ValueArray[i] + ", ";
                    else
                        Values += ValueArray[i];
                }
            }

            string Command = "insert into " + TableName + " (" + TableName + ") values (" + Values + ")";
            SQLiteCommand SqliteCommand = new SQLiteCommand(Command, Connection);
            return SqliteCommand.ExecuteNonQuery();
        }

        public int CreateTable(SQLiteConnection Connection, string TableName, string Columns)
        {
            string Command = "CREATE TABLE " + TableName + " (" + Columns + ")";
            SQLiteCommand SqliteCommand = new SQLiteCommand(Command, Connection);
            return SqliteCommand.ExecuteNonQuery();
        }

        public bool CreateDatabase(string Path, string FileName)
        {
            if (FileName.EndsWith(".sqlite") == false)
                FileName += ".sqlite";
            if (Path.EndsWith("\\") == false)
                Path += "\\";

            SQLiteConnection.CreateFile(System.IO.Path.Combine(Path, FileName));

            if (System.IO.File.Exists(System.IO.Path.Combine(Path, FileName)) == true)
                return true;
            else
                return false;
        }

        public bool CheckDatabase(string Path)
        {
            if (System.IO.File.Exists(Path) == true)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }