btree, Sql Server - rextester

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IF OBJECT_ID('[dbo].[btree]', 'U') IS NOT NULL 
    DROP TABLE [dbo].[btree];
GO

CREATE TABLE [dbo].[btree]
(
  id INT PRIMARY KEY
, parent_id INT REFERENCES [dbo].[btree] ([id])
, name NVARCHAR(20)
);
GO

INSERT INTO [btree] VALUES (1, null, '1 Root');
INSERT INTO [btree] VALUES (2,    1, '1.1 Group');
INSERT INTO [btree] VALUES (3,    1, '1.2 Group');
INSERT INTO [btree] VALUES (4,    2, '1.1.1 Group');
INSERT INTO [btree] VALUES (5,    2, '1.1.2 Group');
INSERT INTO [btree] VALUES (6,    3, '1.2.1 Group');
INSERT INTO [btree] VALUES (7,    3, '1.2.2 Group');
INSERT INTO [btree] VALUES (8,    4, '1.1.1.1 Items');
INSERT INTO [btree] VALUES (9,    4, '1.1.1.2 Items');
INSERT INTO [btree] VALUES (10,   5, '1.1.2.1 Items');
INSERT INTO [btree] VALUES (11,   5, '1.1.2.2 Items');
INSERT INTO [btree] VALUES (12,   6, '1.2.1.1 Items');
INSERT INTO [btree] VALUES (13,   6, '1.2.1.2 Items');
INSERT INTO [btree] VALUES (14,   7, '1.2.2.1 Items');

;WITH tree AS
(
	SELECT c1.id, c1.parent_id, c1.name, [level] = 1
	FROM dbo.[btree] c1
	WHERE c1.parent_id IS NULL
	UNION ALL
	SELECT c2.id, c2.parent_id, c2.name, [level] = tree.[level] + 1
	FROM dbo.[btree] c2 INNER JOIN tree ON tree.id = c2.parent_id
)
SELECT tree.level, tree.id, parent_id, REPLICATE('  ', tree.level - 1) + tree.name AS description
FROM tree
OPTION (MAXRECURSION 0)
;

View schema
Execution time: 0,02 sec, rows selected: 14, rows affected: 14, absolute service time: 0,17 sec