'Split, Sort & Collapse' is, happily, not a description of the intrepid Fabiano after his epic series of articles about the ShowPlan operators. With renewed stamina, Fabiano continues his mission to describe all the major operators by explaining the Trivial Plan and the power of unique indices.
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The most persistent struggle in data processing has been to ensure clean data. There are many ways that data can be incorrect and a database must check, as best it can, that the data is correct. The CHECK constraint is ideally suited for this sort of work, and the checking routine can become quite complex when dealing with check digits in data.
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It turns out that there are plenty of ways to get data into SQL Server from websites, whether the data is in tables, lists or DIVs Phil finds to his surprise that it is easier to use Powershell and the HTML Agility Pack, than some of the more traditional approaches. Web-scraping suddenly becomes more resilient.… Read more
So much has been written about SQL Injection, yet such attacks continue to succeed, even against security consultants' websites. The problem is often that only part of the solution is described, whereas the best practice requires the use of defense in depth.
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So, given the many good reasons for using Version Control systems for managing the changes in database applications, how does one go about the rather different routines of team development, such as testing, continuous integration, and managing data? What are the issues you're likely to face?
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SQL Server is able to make implicit use of parallelism to speed SQL queries. Quite how it does it, and how you can be sure that it is doing so, isn't entirely obvious to most of us. Paul White begins a series that makes it all seem simple, starting at the gentle level of counting Jelly Beans
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The trouble with using BCP for reading data into SQL Server is that BCP is a command-line program. Fortunately, the same input functionality is available from TSQL within SQL Server. In fact there are two ways, and it is not always obvious which to use.… Read more
When Fabiano agreed to undertake the epic task of describing each showplan operator, none of us quite predicted the interesting ways that the series helps to understand how the query optimiser works. With the Merge Interval, Fabiano comes up with some insights about the way that the Query optimiser handles overlapping ranges efficiently… Read more
Of the big four DML statements in SQL Server, the DELETE is the one least written about. This is odd considering the extra power conferred on the statement by the addition of the WITH common_table_expression; and the OUTPUT clause that essentially allows you to move data from one table to another in one statement.
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Did you ever wonder how and why your indexes affect the performance of joins? Once you've read Fabiano's unforgettable explanation, you'll learn to love the MERGE operator, and plan your indexes so as to allow the Query Optimiser to use it.
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With SQL Server 2005, SQL Server introduced some of SQL's window functions, that apply, not to the full set, but a partitioned 'window'. Although the ROW_NUMBER, RANK, NTILE and DENSE_RANK bring great power to TSQL, the full versatility will not be available until SQL Server delivers the full implementation. As usual, Robert Sheldon explains all.
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The use of the comma-separated list of parameters to a SQL routine, that Phil Factor calls the 'comedy-limited list, is a device that makes seasoned SQL Database developers wince. The best choice of design for passing variable numbers of parameters or tuples to SQL Routines varies according to the importance to you of SQL Standards. Joe Celko discusses the pros and cons of the front-runners
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Fabiano introduces another ShowPlan operator that is used to build a query plan, or perform an operation specified in the DML. Once again, Fabiano demonstrates why it is important to be aware of these operators when getting queries to perform well.… Read more
The INSERT statement in SQL Server is versatile. It now allows the insertion of multiple rows of literal values. It also provides the output clause that solves a number of common problems such as ascertaining the value of identity fields, and other calculated fields in tables, or for auditing the rows that are added to tables. Robert, once again, gives a clear introduction. … Read more
Jonathan Lewis is an Oracle expert who is recording his exploration of SQL Server in a series of articles. In this fourth part, he turns his attention to clustered indexes, and the unusual requirement SQL Server seems to have for the regular rebuilding of indexes. … Read more
Fabiano continues his mission to explain the Query Optimiser in practical terms, describing, one week at a time, all the major Showplan Operators used by SQL Server's Query Optimiser to build the Query Plan. He discusses the Stream Aggregate function and shows how easy it is to get performance gains in GROUP BY clauses by choosing the right index.… Read more
When the SQL MERGE statement was introduced in SQL Server 2008, it allowed database programmers to replace reams of messy code with something quick, simple and maintainable. The MERGE syntax just takes a bit of explaining, and Rob Sheldon is, as always, on hand to explain with plenty of examples.… Read more
In retrospect, it was probably the inclusion of the OUTPUT clause in the MERGE statement that gave SQL Server 2008 its most powerful SQL enhancement.. It isn't the easiest of features to explain, but Bob does it in his usual clear and careful way.… Read more
To make progress as a relational Database programmer, you have to think in terms of sets, rather than lists, arrays or sequential data. Until that point, you'll feel the need to pass lists, arrays and the like to functions and procedures. Joe suggests some unusual ways around the difficulty and broods on the power of the VALUES constructor.… Read more
