Adam Machanic, Boston-based independent database consultant, writer, and speaker, shares his experiences with programming, performance tuning, and optimizing SQL Server 2000, 2005, and 2008, in conjunction with related technologies such as .NET.
Originally posted
here.
In the
article on handling bitmasks I posted the other day, I made
a fatal error in the splitBitmask function. The function treated the low byte as the first byte, instead of the high byte. Therefore:
0x01 != 0x0001
... and that is not good!
So here's a corrected version that fixes the problem:
CREATE FUNCTION dbo.splitBitmask
(
@Bitmask VARBINARY(4096)
)
RETURNS TABLE
AS
RETURN
(
SELECT Number
FROM BitmaskNumbers
WHERE (SUBSTRING(@Bitmask, DATALENGTH(@Bitmask) - Byte + 1, 1) & BitValue) = BitValue
AND Byte <= DATALENGTH(@Bitmask)
)
GO
More to come soon... Bit shifting, logical operators, and other fun ways to annoy this guy:
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About Adam Machanic
Adam Machanic is a Boston-based independent database consultant, writer, and speaker. He has been involved in dozens of SQL Server implementations for both high-availability OLTP and large-scale data warehouse applications, and has optimized data access layer performance for several data-intensive applications. Adam has written for numerous web sites and magazines, including SQLblog, Simple Talk, Search SQL Server, SQL Server Professional, CoDe, and VSJ. He has also contributed to several books on SQL Server, including "Expert SQL Server 2005 Development" (Apress, 2007) and "Inside SQL Server 2005: Query Tuning and Optimization" (Microsoft Press, 2007). Adam regularly speaks at user groups, community events, and conferences on a variety of SQL Server and .NET-related topics. He is a Microsoft Most Valuable Professional (MVP) for SQL Server and a Microsoft Certified IT Professional (MCITP).