SQL Server +0 and -0

• by john_wong_ca

• John Huang’s Blog

This is a very interesting error happened in one of my clients’ databases. Their database has been running for at...

2013-04-30

1,541 reads

SQL Saturday #198 Feb 16, 2013

• by john_wong_ca

• John Huang’s Blog

SQL Saturday 198, http://www.sqlsaturday.com/198/ ; is coming to Vancouver Feb 16 this year.  As of now, 56 sessions are collected from...

2013-01-09

812 reads

NULL Values Impact the Performance of MAX() and MIN()

• by john_wong_ca

• John Huang’s Blog

We know that we need to take special attention about NULL values while writing queries because they may lead us into...

2012-12-26

1,754 reads

Inserted and Deleted are One Table?

• by john_wong_ca

• John Huang’s Blog

Inserted and deleted tables are 2 pseudo tables preseting the before and after images of modified rows. They can only...

2012-10-17

2,337 reads

Update with UPDLOCK

• by john_wong_ca

• John Huang’s Blog

Do you think it’s a good idea to add UPDLOCK hint to the table which will be modified in an...

2012-10-10

1,302 reads

Have You Seen This Error?

• by john_wong_ca

• John Huang’s Blog

location: AppendOnlyVerStoreMgr.cpp:776
Expression: 0
SPID: 64
Process ID: 4912
Description: Cannot locate version record and page is not allocated. Status = 3
Msg 3624, Level 20,...

2012-09-10

1,137 reads

Get Dependent Databases, Tables, Columns…

• by john_wong_ca

• John Huang’s Blog

Quite often people need to write a new T-SQL application to replace an existing one for various reasons. For instance,...

2012-07-06 (first published: 2012-06-29)

4,132 reads

Locking Behavior – Foreign Keys

• by john_wong_ca

• John Huang’s Blog

With Snapshot (read committed snapshot and snapshot isolation level) enabled, when data reading on a table takes place, if any...

2012-06-26

2,720 reads

Bug? Can’t Pass TVP to SQL Function Twice

• by john_wong_ca

• John Huang’s Blog

I run into a bug recently with SQL Server 2012. I believe this exists in SQL Server 2008 as well....

2012-06-20

1,071 reads

DBCC WritePage

• by john_wong_ca

• John Huang’s Blog

DBCC WritePage is a dangerous undocumented DBCC command. It’s useful in your sandbox to change data, crash objects, and do...

2011-11-23

2,459 reads