What is the deal with all these different SQL Languages?

ISO/IEC has released several versions of the (ANSI) SQL standard. Each is a list of requirements adopted by representatives from industry in 60 countries. ANSI, the American National Standards Institute, is the official U.S. representative to ISO. The SQL standards are implemented in varying degrees in subsequent releases from major database platform vendors.


The major vendors benefit from the standard because it partially completes requirements gathering for future releases. Their products are made of interpretations and compromises built on prior interpretation and compromise. Marketing is a factor driving adoption of standards. Why prioritize standards customers haven’t asked for?


Then there are the “disruptive innovators.” In the world of database this usually means that either: a paper critical of a standard or a vendor implementation of a standard launched a startup.  Popular disruptions often find their way into the major vendor’s products.


These disruptors have been branded NoSQL and BigData. NoSQL offered document store, graph, key-value, and object databases to name a few. BigData offered relaxed concurrency for high volume high speed data. Most of these functionalities have already been included in recent release from the major vendors.


The major vendors of database platforms are IBM, Microsoft, Oracle, and SAP. IBM has DB2. Microsoft has SQL Server and Azure SQL. Oracle has Oracle, as well as MySQL which they acquired with Sun Microsystems. And SAP has SAP HANA.


These vendors offer a whole host of products in the ERP, CRM, HRM, DSS, and Analytics spaces (to name a few) most of which require a database). There are third party vendors offering Enterprise Resource Planning (ERP), Customer Relationship Management (CRM), Human Resources Management (HRM), Decision Support Systems (DSS) and Analytics Systems each of which will have some degree of preference for one of the major vendors.


What is done with data and with which software drives adoption. This is marketing engineering. Other factors that contribute to adoption is compatibility. Until recently Microsoft’s SQL Server did not run on Linux, but most every other major vendor’s software ran on both Linux and Windows. Licensing can also affect adoption. SQL Server is popular in part because of the ubiquity of Windows and Microsoft Office, each of which contribute to volume licensing requirements that lower the cost of software and support.


In my humble opinion, SQL Server, Oracle, and IBM DB2 are the best documented. Documentation should be a driver in adoption. A poorly documented system is one that is destined to fail miserably.


What is SQL and Why should I care?

SQL stands for Structured Query Language. Some people prefer to spell it out, S-Q-L, others pronounce it sequel [ˈsēkwəl]. SQL is a standard defined and maintained by the American National Standards Institute (ANSI) as well as International Organization for Standards – International Electrotechnical Commission (ISO/EIC). It comes in numerous variants. These are specific to database systems that implement the standard. There are also numerous SQL like languages.


You should care about SQL if you care about data. SQL primarily functions to describe tables of data. It instructs the database system to create, modify, or retrieve some form of table. Is it possible to write SQL that in no way describes a table? Feel free to find and share cases that don’t fit neatly into “tables”?


Understanding tables will help you understand how you can use SQL. SQL has the keywords CREATE, ALTER, and DROP which can be used to make, change, and destroy tables. These keywords can make other objects like functions, stored procedures, and views (users, logins, triggers, audits, connections, … etc.). While technically not tables, they do exist as rows in tables. These keywords can also be used to make indexes which help table operations be performed more efficiently.


Often, a person will be working with tables that already exist. In these cases, the SQL keywords SELECT, INSERT, UPDATE and DELETE will be used to perform CRUD operations. CRUD stands for Create, Read, Update, and Delete. These operations are often being performed by multiple users simultaneously.


Multi-user access is an important consideration. The SQL standard prescribes Isolation Levels. These are approaches to the problems that happen with multiple user simultaneous access. These contribute to ACID compliance. ACID stands for Atomicity, Consistency, Isolation and Durability. This is what a lot of “NoSQL” languages tend to do without. Without it, it’s a fast paced free for all that can leave a mess. With it deadlocking and blocking can occur.


These issues shouldn’t stop a data user from becoming an SQL Pro. They just mean you should consult a SQL Pro with experience and keep focused on what matters. SQL itself is by design simple and intuitive (maybe).


SQL is declarative. A user need not know how to create locks or latches, nor which algorithms most efficiently sort, sample, or join. SQL allows the user to declare the state they wish data to be in. The database platform determines based on the structures in play, the statistics available, and other factors how best to fill the request.

When operations are performed the database uses a state transformation known as a transaction. In short, a transaction is an all or nothing operation. It allows multiple tables to be either a start or finish state. Transactions are self-contained. The state is either as it was or as it was intended. Transactions operate independent of other transactions. They are permanent once completed.


In short SQL is a language for working with data in database systems. SQL allows you to describe what you want and get it. It allows a whole host of technical issues to be left to software engineers, database architects and administrators.

Where is my SQL Server Configuration Manager?

If you are asking yourself that, you are administering SQL Server 2016 network or services for the first time, or found some dusty old instance that should be decommissioned. In the latter case you are looking for Enterprise Manager, and perhaps someone to accept responsibility for the change control request.

In the case of 2016 you may not have noticed but its where it has always been.

“What? No it’s not. I looked in the SQL Server folder of the start menu.” you say.

Ok. It’s not there but it is still a snap-in for Microsoft Management Console (MMC).

If you never knew that there was a such thing as MMC, you only need a few quick steps to get up and running.

First, you press the Windows key on you keyboard. If you are unfortunate enough to not have one of those you click the start menu.

Next you type MMC. If you notice that a familiar little icon of a toolbox on a window didn’t appear but instead it you highlighted something starting with the letter M, then something else, then perhaps something starting with a C, you might want to think about Windows end of support dates. For now, click run, and then type MMC.

In either case you should be able to launch the MMC.exe console.

Unless, someone configured it for you, the console is going to be this rather uninteresting window:

2017-06-20_20-34-18 Plain Old MMC

If you open the file menu and select add/remove snap-in…. (CTRL+M for keyboardists), you will be presented with the Add or Remove Snap-ins dialog.

2017-06-16_19-45-23 SQL Configuration Manager

From there you can scroll down to SQL Server Configuration Manager. Click add. Click Ok. And now you have SQL Server Configuration Manager.

2017-06-20_20-44-10 SQL Server Configuration Manager.

As you may have guessed you can add other useful snap-ins  like (Performance Monitor, Disk Management, Event Viewer, Services, WMI Control, ADUC, RSAT, or Computer/Server Management).

2017-06-20_20-46-19 But wait there's more

In case you missed it, while we were adding all those cool snap-ins most of which are  part of Computer/Server Management, you can select the local computer or a remote server.

2017-06-20_20-55-17 Remote management

If you like that you can save the console and give it a name. You can also configure folders to hold different groups of servers. You can also create favorites and organize the relationships between the snap-ins to allow you to drill down through common troubleshooting steps. For example you might like to see a performance monitor snap-in configured to view IO related counters as a child of disk management.

MMC is great tool. Now you have to use it. Try and enjoy.


Temporal Tables. Yes, Please.

SQL Server 2016 and Azure SQL Database implement a new feature called Temporal Tables, not to be confused with Temporary Tables. This feature implements in a common sense fashion the needs of database applications to maintain a history of changes not just for auditing but for the purpose of analytics.

Temporal Tables allow a user to leverage the FOR SYSTEM_TIME clause when querying a table which was created with the SYSTEM_VERSIONING = ON. Users can also query the temporal history table directly, which is necessary for history values with a duration of zero (e.g. rows updated multiple times in a single transaction).

Are You Ready for Some Football?

In honor of Super Bowl 50 I put together a quick visualization with Power Map in Excel 2016. We can see the scores of each team by the size of the dot on their cities. We can also see the number of people in attendance as the height of the bar on the hosting city.

SQL Server Snippets

Yesterday, working with a colleague the topic got steered towards the use of snippets in SQL Server 2012+. My reflex was to let my colleague know that my blog is wonderful source for all things SQL Server. Much to my chagrin, for all of the snippets I have, I have written a blog post about it.

Visual Studio has had code snippets for a decade now, but SQL Server only got them a version and a half ago. I might imagine that having templates was the excuse given for not pursuing them but I am glad we have them now. The tools menu will lead you to the Code Snippets Manager… from there you can find the path to built-in snippets. These provide good fodder for creating your own.

There are two types of snippets. Expansion snippets insert the code snippet where the cursor is. Surround snippets wrap code around highlighted SQL. Both have arguments that allow you to tab through variable portions and update multiple references in a single place. Let’s take a look at a simple expansion snippet.

<?xml version="1.0" encoding="utf-8" ?>
<CodeSnippets  xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
<_locDefinition xmlns="urn:locstudio">
    <_locDefault _loc="locNone" />
    <_locTag _loc="locData">Title</_locTag>
    <_locTag _loc="locData">Description</_locTag>
    <_locTag _loc="locData">Author</_locTag>
    <_locTag _loc="locData">ToolTip</_locTag>
	<CodeSnippet Format="1.0.0">
			<Title>Create Temporary Table</Title>
			<Description>Creates a temporary table.</Description>
			<Author>Thomas W Marshall</Author>
                                	<ToolTip>Name of the Table</ToolTip>
                                	<ToolTip>Name of the Columneter</ToolTip>
                                	<ToolTip>Data type of the Columneter</ToolTip>
                                	<ToolTip>Name of the Column</ToolTip>
                                	<ToolTip>Data type of the Column </ToolTip>
			<Code Language="SQL"><![CDATA[

IF EXISTS(SELECT name FROM tempdb.sys.objects WHERE object_id=OBJECT_ID('tempdb..#$TableName$') AND type = N'U') DROP TABLE #$TableName$;
    $Column1$ $Datatype_Column1$,
    $Column2$ $Datatype_Column2$


You can copy the above XML into a file with the extension .snippet and save it in the Code Snippets\SQL\My Code Snippets directory. You should then see it in the Code Snippets manager. Alternatively, you can import a .snippet file using the Code Snippets manager. Once the snippet has been installed whenever you strike the expansion chord CTRL+K,X in SQL Server Management Studio you will see it in the My Code Snippets folder of the fly-out menu.

In the above XML document we can see a field in the declarations for each of the variable fields. Once you have chosen to insert the snippet those declare fields are linked by there name appearing between $’s. This allows you to change the value in one and have all instances of that name update. You can also tab to the next name.

Requirements Analysis

In an earlier post we started generating prime candidates testing only numbers of the form 6k+1 or 6k-1 less than or equal to the square root of the next integer. The reason we were doing this is that all prime numbers greater than 3 are of the form 6k+1 or 6k+2 and we only have to modulo test primes. The reason we only have to test primes is that the Fundamental Theorem of Arithmetic indicates that all non-prime numbers greater than one is the product of primes.

What that means is that we only have to modulo test prime numbers. Of course in pursuing that particular optimization we actually neglected to test first whether the next integer we were testing was of the form 6k+1 or 6k-1. The point of this post is to highlight how in the course of developing SQL (or any other code for that matter), we can read our requirements in a number of ways and will need to step out of it and reconsider whether our first reading was complete or even correct.

Consider the following statements: “We only need to modulo test primes for a given integer.” and “We need to test whether or not their exists a prime factor for a given integer.” These two statement mean essentially the same thing. When combined with the form of primes being 6k+1 or 6k-1 led us to skip testing the integer itself for being of that form, but assume we have already filled a prime table to a certain number and are testing the prime candidates. Those two statements can lead us to two very different approaches to SQL.

The first statement: “We only need to modulo test primes for a given integer.” could lead us to write something like:


SELECT TOP 1 1 FROM prime_candidates pc INNER JOIN primes p ON pc.p % p.p = 0 WHERE pc.p=@n

Whereas the second statement: “We need to test whether or not their exists a prime factor for a given integer.” might lead us to write something like:

SELECT TOP 1 1 FROM primes p WHERE @n % p = 0

Since our requirement was to test for prime factors of a given integer and not to produce a set of prime factors performing we do not need the non-equijoin that produces a less efficient execution plan.


Seeks that lead to lookups are usually more efficient than scans. Of course unnecessary operations are inherently inefficient. In either case it is important to test that we do in fact get the results we expect.

Naming Conventions in SQL Server

It seems that everyone has an opinion on naming conventions. Microsoft even has a few recommendations. You would think with 256 (or 128 or 30) characters it would be simple to devise an apt system for describing database objects.

SELECT TYPE_NAME(system_type_id) [base_type], max_length FROM sys.types WHERE name = ‘SYSNAME’;

Of course, we might not want to use our screen real estate on object explorer. We also might not want to use that real estate up for a single column name (especially if that column was a bit flag). Fortunately, we have options. In addition to being able to use management studio to filter objects, we can us schemas to group objects and alias data types to categorize.

An example case for using schemas might be to create separate schemas for staging updates and deletes in a CDC based warehouse loads. An example for using alias data types might be differentiate between date types that are application data and date types that are row level metadata (e.g. inserted or updated date).