Sometime you want to hide certain values by replacing them with NULL values. SQL Server offers you a nice function called NULLIF() to do this:

NULLIF(expression, value)

-- Returns NULL if "expression" equals to value"

-- Returns "expression", otherwise

NULLIF() can be viewed as the reverse function of ISNULL(). The tutorial script below shows you a good example of using NULLIF():

USE GlobalGuideLineDatabase;

GO

SELECT id, counts FROM ggl_links;

GO

id  counts

----------- -----------

101  NULL

102  8

1101  NULL

202  NULL

2101  NULL

2102  NULL

301  NULL

302  NULL

-- converting NULL to 0

UPDATE ggl_links SET counts=ISNULL(counts,0);

GO