In the classic teaching materials you will always find the same approaches and examples to introduce beginners to the basics of data source links (JOINS) or to explain constructs such as pivoting and recursion to advanced users. However, the experience of Torsten Ahlemeyer as a consultant for T-SQL shows in countless company assignments that there is immense potential for "wrong" queries. These are particularly tricky because they are syntactically correct but do not deliver the desired and expected result - which can be difficult to discover with large amounts of data. Such inaccuracies can cause enormous damage if the relevant technical relevance (e.g. financially critical data) is appropriate.

With just a few tricks you can train the safe use of the JOIN types, write down every recursion immediately, convert line-by-line information into comma-separated lists and pivot or cancel it. In this session we will look at all of this using just one example, which we continue to condense into the desired graphical output. We also deal with issues such as filtering, sorting, grouping or subselects... Since the result does not just consist of an endless table with some mathematical values, but rather represents a graphic preparation of the underlying data, the effects of implementation inaccuracies are immediately visible.