i as busy the last few month. I finally started my own SQL based youtube Channel.

The first videos will be for absolute beginners, meaning it won't be interesting  for you guys. But stay tuned since i plan to do the MCSE SQL Server: Data Plattforms this year. So there are many interesting topics in the pipeline.

Also think of SQL Server 2016 and new features. So 2016 will provide us with many new fancy things.

If you have a colleague that struggles hard with SQL please provide him the link to my new Youtube Channel:



Stay tuned and thanks for reading my blog. ....

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There are many time and date formats in sql server with different ranges, accuracies, storage sizes and user defined fractional second precisions.

Below is a short overview.


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Today I want to address two very common issues when it comes to query plan tuning or query optimizing. At first I will have a look on implicit converts and the consequences. The second topic is all about the query optimizer and how quick one can have bad execution plans. For both issues I will five advice what to do in such a situation.

Implicit converts

Whenever you tell SQL Server to compare or evaluate two expressions that have different incomparable data types the SQL Server will adjust one of the expressions to a fitting data type so it can evaluate the expression. A very basic example is comparing integer with float numbers. Most likely the integer number will get transferred into a floating number to then compare it with the other float number.

But in SQL this can have fatal consequences. At first the optimizer does not know how a transformed column is ....

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When I started with my first real job in IT after my graduation I actual was hired as a C# dot net developer. I soon realized that the job description was a bit wrong. Instead of dealing with much C# Code I had actually to deal with a kind of data warehouse. C# was only used to do the ETL (extract transform load) processes. Obviously my former company had implemented ETL tools themselves instead of using existing ones.

However since I specialized in databases during my master and wrote my master thesis about sql it actually really suited me. But I was confronted with SQL Server 2008 and later SQL Server 2012 and I only knew SQL from MySQL and ORACLE. But of course I lacked in practical skills.

So in the end I decided to achieve the Microsoft Certified Solutions Associate (MCSA) Certificate to bring my knowledge up to date and learn some ....

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Locking in SQL Server 2012

The default transaction level in sql server 2012 is READ COMITTED. That transaction level uses a pessimistic approach meaning readers can block writers, writers can block writers and writers can block readers.
Is it basically the opposite approach of optimistic approaches like providing row versions i.e. snapshot isolation level.

However in this session we want to focus on how SQL Server maintains consistency in a multi-user environment. The answer is simple: locks.

But how are locks actually handled. Well there is a bunch of information about locking.

First there are locks and latches. Most locks are being held until the end of transactions.
Latches are being held until the specific operation is over. Locks are used to maintain logic consistency. Latches are used to maintain physical consistency.
We will focu ....

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