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SQL Server R Services: Digging into the R Language

It is not just the analytic power of R that you get from using SQL Server R Services, but also the great range of packages that can be run in R that provide a daunting range of graphing and plotting facilities. Robert Sheldon shows how you can take data held in SQL Server and, via SQL Server R Services, use an R package called ggPlot that offers a powerful graphics language for creating elegant and complex plots.… Read more

SQL Data Aggregation Aggravation

When we have to deal with and store a lot of data, it makes sense to aggregate it so that we store only the information we actually need. If we get this right, this works well, but the design of the system takes care and thought because the problems can be subtle and various. Joe Celko describes some of the ways that things can go wrong and end up providing incorrect, inaccurate or misleading results.… Read more

SQL Graph Objects in SQL Server 2017: the Good and the Bad

Graph databases are useful for certain types of database tasks that involve representing and traversing complex relationships between entities. These can be difficult to do in relational databases and even trickier to report on. Until now, we have had the choice of doing it awkwardly in SQL Server or having an ancillary database to tackle this type of task. SQL Server 2017 will be bringing graph capabilities to the product but will these features prove to be good enough to allow us to dispense with specialised Graph databases? Dennes Torres decided to find out.… Read more

The Basics of Good T-SQL Coding Style – Part 3: Querying and Manipulating Data

SQL was designed to be a third-generation language, expressed in syntax close to real language, because it was designed to be easy for untrained people to use. Even so, there are ways of expressing SQL Queries and data manipulation in ways that make it easier for the database engine to turn into efficient action. and easier for your colleagues to understand. Robert Sheldon homes in on data querying and manipulation and makes suggestions for team standards in SQL Coding.… Read more

Is It Time To Stop Using IsNumeric()?

The old system function IsNumeric() often causes exasperation to a developer who is unfamiliar with the quirks of Transact SQL. It seems to think a comma or a number with a 'D' in the midde of it is a number. Phil Factor explains that though IsNumeric has its bugs, it real vice is that it doesn't tell you which of the numeric datatypes the string parameter can be coerced into, and because it doesn't check for overflow. Phil comes to the rescue with a couple of useful alternatives, one of which works whatever version of SQL Server you have, and which tell you what datatype the string can be converted to.… Read more

Database Code Analysis

Database code analysis will reduce the number of 'code smells' that creep into your database builds. It will alert the team to mistakes or omissions, such as missing indexes, that are likely to cause performance problems in production. It will allow the Governance and Operations team visibility into production readiness of the code, warning them of security loopholes and vulnerabilities. William Brewer describes the two technical approaches to database code analysis, static and dynamic, and suggests some tools that can help you get started.… Read more

SQL Server R Services: The Basics

It is possible to do a great deal with R within SQL Server, but it is best to start by doing analysis in R on numeric data from SQL Server and returning the results to SQL Server. There is great value to be gained even with this basic foundation. Robert Sheldon is on hand to give you a kick start with the first in his series on beginning with R in SQL Server.… Read more

The Basics of Good T-SQL Coding Style – Part 2: Defining Database Objects

Technical debt is a real problem in database development, where corners have been cut in the rush to keep to dates. The result may work but the problems are in the details: such things as inconsistent naming of objects, or of defining columns; sloppy use of data types, archaic syntax or obsolete system functions. With databases, technical debt is even harder to pay back. Robert Sheldon explains how and why you can get it right first time instead.… Read more

Statistics in SQL: The Kruskal–Wallis Test

Before you report your conclusions about your data, have you checked whether your 'actionable' figures occurred by chance? The Kruskal-Wallis test is a safe way of determining whether samples come from the same population, because it is simple and doesn't rely on a normal distribution in the population. This allows you a measure of confidence that your results are 'significant'. Phil Factor explains how to do it.… Read more

SQL Server User-Defined Functions

User-Defined Functions (UDFs) are an essential part of the database developers' armoury. They are extraordinarily versatile, but just because you can even use scalar UDFs in WHERE clauses, computed columns and check constraints doesn't mean that you should. Multi-statement UDFs come at a cost and it is good to understand all the restrictions and potential drawbacks. Phil Factor gives an overview of User-defined functions: their virtues, vices and their syntax.… Read more

Simple SQL: Attribute Splitting

If the design of a relational database is wrong, no amount of clever DML SQL will make it work well. Dr. Codd’s Information Principle is that you have, inside the entity tables, the columns that model the attributes of that entity. The columns contain scalar values. Tables that model relationships can have attributes, but they must have references to entities in the schema. You split those attributes at your peril. Joe Celko explains the basics.… Read more

Visual Checks on How Data is Distributed in SQL Server

There are many reasons for wanting to know how data is distributed. Sometimes you just want a rough idea of the way that data is distributed in a column. You may think, wouldn't it be nice to have a SQL function that just showed you roughly what the distribution was, graphically, in the results pane. Phil Factor thought that was well and turned the vague wish into reality.… Read more

The Basics of Good T-SQL Coding Style

TSQL Code must work properly and efficiently. That's not enough though. Unless you are working alone, have perfect memory and plan to never change job, then you need to comment and document your code, it must be inherently readable, well laid out, use informative and obvious names, and it must be robust and resilient; written defensively. It must not rely on deprecated features of SQL Server, or assume particular database settings. Robert Sheldon starts a series of articles that explains the basics.… Read more

Generating HTML from SQL Server Queries

You can produce HTML from SQL because SQL Server has built-in support for outputting XML, and HTML is best understood as a slightly odd dialect of XML that imparts meaning to predefined tags. There are plenty of edge cases where an HTML structure is the most obvious way of communicating tables, lists and directories. Where data is hierarchical, it can make even more sense. William Brewer gives a simple introduction to a few HTML-output techniques.… Read more

Statistics in SQL: Kendall’s Tau Rank Correlation

Statistical calculations in SQL are often perfectly easy to do. SQL was designed to be a natural fit for calculating correlation, regression and variance on large quantities of data. It just isn't always immediately obvious how. In the second of a series of articles, Phil factor shows how calculating a non-parametric correlation via Kendall's Tau or Spearman's Rho can be stress-free.… Read more

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