The XML data type, introduced in SQL Server 2005, is a powerful construct. When used wisely, it can provide useful extensions to SQL Server. Robert Sheldon, in the first part of a series, describes how create and index a typed XML column in a table, and discusses when you should consider using an XML Datatype.… Read more
When SQL Server introduced Window Functions in SQL Server 2005, it was done in a rather tentative way, with only a handful of functions being introduced. This was frustrating, as they remove the last excuse for cursor-based operations by providing aggregations over a partition of the result set, and imposing an ordered sequence over a partition. Now, with SQL Server 2012, we are soon to enjoy a full range of Window Functions. They are going to make for some much simpler SQL queries.… Read more
If you suffer from runaway queries, if you have several database applications with unpredictable fluctuation in workload, or if you need to ensure that workloads get the memory or CPU they need according to certain priorities, then you need Resource Governer, and you need Roy Ernest's clear explanation of the technology.… Read more
SQL is a powerful tool for querying data, and for aggregating it. However, you can't easily use it to draw inferences, to make predictions, or to tease out subtle correlations. To provide ever more sophisticated inferences to businesses, the race is on to combine the power of the relational model with advanced statistical packages. Both IBM and PostGres are ready with solutions. And SQL Server? Hmm...… Read more
As a DBA and hiring manager, Chris Shaw has been on those sides of the recruitement process. As an MVP and active member of the SQL Server community, he knows what resources are available to help DBAs hone their abilities. Who better to guide you through the many paths to developing your DBA skillset?… Read more
'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.
… Read more
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.
… Read more
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.
… Read more
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
… Read more
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?
… Read more
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.
… Read more
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.
… Read more
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.
… Read more
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
… Read more
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
