How SPARSE column saves space in database table.

Example of how SPARSE column saves space in database table.

CREATE TABLE UnSparsed(ID INT IDENTITY(1,1),
FirstCol INT,
SecondCol VARCHAR(100),
ThirdCol SmallDateTime)
GO
CREATE TABLE Sparsed(ID INT IDENTITY(1,1),
FirstCol INT SPARSE,
SecondCol VARCHAR(100) SPARSE,
ThirdCol SmallDateTime SPARSE)
GO
DECLARE @idx INT = 0
WHILE @idx < 50000
BEGIN
INSERT INTO UnSparsed VALUES (NULL,NULL, NULL)
INSERT INTO Sparsed VALUES (NULL, NULL, NULL)
SET @idx+=1
END
GO
sp_spaceused 'UnSparsed'
GO
sp_spaceused 'Sparsed'
GO
DROP TABLE UnSparsed
GO
DROP TABLE Sparsed
GO