|By Mujtaba Syed||
|July 6, 2004 12:00 AM EDT||
Microsoft is releasing a new version of SQL Server after a gap of five years. This version (SQL Server 2005) introduces a horde of new attention-grabbing features like native XML storage and querying (using XQuery), CLR integration, SQL Web Services, query notifications, and the Service Broker. Apart from these high-profile enhancements, SQL Server 2005 also comes with improved T-SQL support.
Overview of T-SQL Enhancements
Most of SQL Server 2005's T-SQL enhancements focus on offering greater expressiveness to queries. We will look at each of these individual enhancements in detail. The list of enhancements includes:
- Relational operators
- Recursive queries
- XML showplan
- Snapshot isolation level
- Data types
- DDL triggers
- DML with output
- Exception handling
SQL Server 2005 introduces three new relational operators: PIVOT, UNPIVOT, and APPLY.
The PIVOT operator is very similar to the TRANSFORM operator that Microsoft Access provides. It is used to rotate rows into columns. The best way to learn about PIVOT is through an example (see Figure 1).
This table lists the sales of a Toyota dealership. Notice that some models have more than one row for a particular year. Now we apply the following SELECT query (which uses the PIVOT operator) to the SalesSummary table. The result we get is shown in Figure 2.
PIVOT (SUM ([UnitsSold]) FOR [Year] IN (, )) AS [T]
The table was PIVOTed on the year column. Notice how the unique year values have taken the shape of columns and the corresponding number of units sold have been summed up.
The UNPIVOT operator does the opposite of what PIVOT does - it rotates columns into rows. Let's say we want to rotate the table in Figure 2 (let's call it Year WiseSalesSummary), so that the number of units sold is displayed for each year. All we have to do is apply the following SELECT query. The result of the UNPIVOT operation is shown in Figure 3.
UNPIVOT (UnitsSold FOR [Year] in (, )) AS T
The APPLY is another new operator available in SQL Server 2005. When used in the FROM clause, it invokes a table-valued UDF for each row of a table. The UDF can optionally use the columns of the table as arguments.
Let's say we have a table called StudentScores that has the Math, Physics, and Chemistry scores of a bunch of students (see Figure 4).
Now, create the Calculate-Grade function, which takes the subject scores of each of the student one at a time and returns the grade of the student.
CREATE FUNCTION [CalculateGrade] (@math AS INT, @physics AS INT, @chemistry AS INT) RETURNS @GradeTable TABLE ([Grade] CHAR (1)) AS BEGIN DECLARE @average FLOAT SET @average = (@math + @physics + @chemistry) / 3 IF @average >= 90 INSERT INTO @GradeTable VALUES ('A') ELSE IF @average >=80 INSERT INTO @GradeTable VALUES ('B') ELSE IF @average >=70 INSERT INTO @GradeTable VALUES ('C') ELSE INSERT INTO @GradeTable VALUES ('F') RETURN END
The following query uses the APPLY relational operator to apply the CalculateGrade function on every row of the StudentScores table. We also pass the Math, Physics, and Chemistry scores to the CalculateGrade function.
SELECT [Name], I.Grade
FROM [StudentScores] AS O
CROSS APPLY CalculateGrade ([Math], [Physics], [Chemistry]) AS I
Figure 5 is an illustrative example of the APPLY operator. There are several ways (many of them better than using the APPLY operator) to achieve the same result.
In SQL Server, a SELECT query can use the TOP option to specify the number of rows that should be returned. The argument to TOP was a constant value of type BIGINT. The TOP option can also be qualified with the PERCENT keyword to specify that a percentage of the total number of rows should be returned by a SELECT query. The argument in this case was a constant value of type FLOAT.
In SQL Server 2005, an argument can be specified using an expression or a query, the only condition being that both should result in a value that is of the correct type.
For example, the following query returns the latest 10 orders from the Orders table in the Northwind database.
DECLARE @NO_OF_ROWS BIGINT
SET @NO_OF_ROWS = 10
SELECT TOP (@NO_OF_ROWS)
ORDER BY [OrderDate] DESC
In SQL Server 2005, the TOP keyword can also be used with INSERT, UPDATE, and DELETE commands. Using TOP to do batch inserts, updates, or delete is more optimal than using the older SET ROWCOUNT method.
An example of using TOP with the DELETE operator would be the following query, which purges the oldest 10,000 rows from TempTable.
DELETE TOP (10000)
ORDER BY [TimeStamp]
SQL Server 2005 introduces Common Table Expressions (CTEs) that allow you to write named table expressions that persist for the duration of a query. The functionality of CTEs is somewhere between derived tables and views.
A CTE can be defined by using the WITH clause, as shown in the following code.
WITH CustomerSales ([CustomerId, [TotalSales])
[CustomerId], SUM ([UnitPrice] * [Quantity] * (1 - [Discount]))
FROM [Orders] AS [O] INNER JOIN
[Order Details] AS [OD]
ON [O].[OrderId] = [OD].[OrderId]
GROUP BY [CustomerId]
SELECT * FROM [CustomerSales]
This query creates a non-recursive CTE called CustomerSales that has two columns: CustomerId and TotalSales. The CTE gets all unique customer ids and the total sales made to them.
The primary purpose of having CTEs is to support recursion. Recursive CTEs improve readability and manageability of complex SQL statements. Recursive CTEs have the ability to traverse recursive hierarchies in a single query. A typical scenario where one would use a recursive CTE would be when a table has a self-referential constraint.
The recursive form of a CTE is as shown:
<SELECT referencing the CTE>
The recursion terminates when the second SELECT block produces an empty result.
The following recursive CTE prints out the name of all employees and their managers found in the Northwind database. The results are shown in Figure 6.
WITH EmployeeManagerCTE ([EmployeeId], [EmployeeName], [ManagerName]) AS ( SELECT [EmployeeId], [LastName] + ', ' + [FirstName], [LastName] + ', ' + [FirstName] FROM employees WHERE [ReportsTo] IS NULL UNION ALL SELECT [E1].[EmployeeId], [E1].[LastName] + ', ' + [E1].[FirstName], [E2].[EmployeeName] FROM [Employees] [E1] INNER JOIN [EmployeeManagerCTE] [E2] ON [E1].[ReportsTo] = [E2].[EmployeeId] ) SELECT * FROM [EmployeeManagerCTE]
SQL Server 2005 has the facility to output a query plan as XML that uses a documented XML schema and carries more information than SQL Server 2000 textual or graphical formats.
The XML query plan output lends itself to various kinds of advanced processing with XQuery, XSLT, DOM, and the CLR.
Snapshot Isolation Level
SQL Server 2000 supports four isolation levels: read uncommitted, read committed, repeatable read, and serializable. SQL Server 2005 introduces a new snapshot isolation level. The snapshot isolation level is based on optimistic concurrency. It holds onto a snapshot of committed data from when the transaction started, allowing non-blocking reads to take place.
SQL Server 2005 introduces a few new data types: XML, VARCHAR (MAX), NVARCHAR (MAX), and VARBINARY (MAX).
The XML data type is a first-class data type in SQL Server 2005 and can be used to define columns, variables, and parameters for stored procedures and user-defined functions. The XML data type can be optionally constrained by an XML schema. SQL Server 2005 also provides built-in XQuery support to query XML data.
The VARCHAR (MAX), NVARCHAR (MAX), and VARBINARY (MAX) data types can store up to 2GB of data and provide alternatives to the existing TEXT, NTEXT, and IMAGE data types respectively.
SQL Server 2005 has extended traditional triggers and enabled them to be fired for DDL operations like CREATE, ALTER, and DROP. These triggers are created, altered, and dropped using similar Transact-SQL syntax as that for standard triggers.
DDL triggers apply to all commands of a single type across a database or server and they execute only after completion of a DDL statement (although they can roll back the transaction to before the execution of the DDL statement that caused their triggering). DDL triggers cannot be INSTEAD OF triggers.
DDL triggers help to enforce development rules and standards for objects in a database; protect from accidental drops; help in object check-in/checkout, source versioning, and log management activities.
An example of a DDL trigger that prevents the dropping of a table is as shown:
CREATE TRIGGER OnDropTable ON DATABASE FOR DROP_TABLE
RAISERROR ('No drops allowed', 10, 1)
DML with Output
SQL Server 2005 introduces the OUTPUT clause that returns inserted, updated, or deleted rows as part of a DML operation. The OUPUT clause can be used with INSERT, DELETE, and UPDATE statements. The "DELETED" and "INSERTED" pseudo-tables can be used to get the pre- and post-operation values.
An example usage is as follows:
SET [Status] = 'Done'
OUTPUT DELETED.*, INSERTED.*
WHERE [Status] = 'In progress'
The DELETED values are not available for INSERT operations while the INSERTED values are not available for the DELETE operations. Both the INSERTED and the DELETED values are available for UPDATE operations.
Exception handling can now be done in SQL Server 2005 by using the very well-known TRY/CATCH paradigm. All errors that set the @@error variable will now throw exceptions. The syntax of using exception handling is as follows:
-- SQL statements
-- SQL statements
TRY/CATCH blocks can also be nested. Error details are available inside the CATCH block through a set of functions - error_number (), error_message (), error_severity (), and error_state (). RAISERROR can be used to re-throw and exception from within a CATCH block.
SQL Server 2005 enhances T-SQL on a number of fronts - it introduces new and important data types, brings more power and expressiveness to SQL querying, provides more procedural capabilities, and improves parallelism.
|CuriousTom 10/11/07 03:25:06 PM EDT|
|sudhakar 08/28/04 05:58:42 AM EDT|
Sorry, i take back my words.
I could find the images, it would have been better to embed the images in the article instead of providing links to them at the end of it.
|sudhakar 08/28/04 05:36:01 AM EDT|
I didnt find any figures (which have been refered) in this article which made the examples given for each feature quite difficult to understand. The pictorial representation of query results would have been very helpful.
Pls. send me an alert to my mailid if you update this article with relevent figures.
According to Forrester Research, every business will become either a digital predator or digital prey by 2020. To avoid demise, organizations must rapidly create new sources of value in their end-to-end customer experiences. True digital predators also must break down information and process silos and extend digital transformation initiatives to empower employees with the digital resources needed to win, serve, and retain customers.
Dec. 10, 2016 04:15 AM EST Reads: 1,389
Amazon has gradually rolled out parts of its IoT offerings in the last year, but these are just the tip of the iceberg. In addition to optimizing their back-end AWS offerings, Amazon is laying the ground work to be a major force in IoT – especially in the connected home and office. Amazon is extending its reach by building on its dominant Cloud IoT platform, its Dash Button strategy, recently announced Replenishment Services, the Echo/Alexa voice recognition control platform, the 6-7 strategic...
Dec. 10, 2016 04:15 AM EST Reads: 571
We're entering the post-smartphone era, where wearable gadgets from watches and fitness bands to glasses and health aids will power the next technological revolution. With mass adoption of wearable devices comes a new data ecosystem that must be protected. Wearables open new pathways that facilitate the tracking, sharing and storing of consumers’ personal health, location and daily activity data. Consumers have some idea of the data these devices capture, but most don’t realize how revealing and...
Dec. 10, 2016 04:00 AM EST Reads: 5,318
IoT solutions exploit operational data generated by Internet-connected smart “things” for the purpose of gaining operational insight and producing “better outcomes” (for example, create new business models, eliminate unscheduled maintenance, etc.). The explosive proliferation of IoT solutions will result in an exponential growth in the volume of IoT data, precipitating significant Information Governance issues: who owns the IoT data, what are the rights/duties of IoT solutions adopters towards t...
Dec. 10, 2016 03:15 AM EST Reads: 500
Whether your IoT service is connecting cars, homes, appliances, wearable, cameras or other devices, one question hangs in the balance – how do you actually make money from this service? The ability to turn your IoT service into profit requires the ability to create a monetization strategy that is flexible, scalable and working for you in real-time. It must be a transparent, smoothly implemented strategy that all stakeholders – from customers to the board – will be able to understand and comprehe...
Dec. 10, 2016 02:15 AM EST Reads: 802
Complete Internet of Things (IoT) embedded device security is not just about the device but involves the entire product’s identity, data and control integrity, and services traversing the cloud. A device can no longer be looked at as an island; it is a part of a system. In fact, given the cross-domain interactions enabled by IoT it could be a part of many systems. Also, depending on where the device is deployed, for example, in the office building versus a factory floor or oil field, security ha...
Dec. 10, 2016 02:00 AM EST Reads: 642
An IoT product’s log files speak volumes about what’s happening with your products in the field, pinpointing current and potential issues, and enabling you to predict failures and save millions of dollars in inventory. But until recently, no one knew how to listen. In his session at @ThingsExpo, Dan Gettens, Chief Research Officer at OnProcess, discussed recent research by Massachusetts Institute of Technology and OnProcess Technology, where MIT created a new, breakthrough analytics model for s...
Dec. 10, 2016 01:30 AM EST Reads: 799
In his general session at 19th Cloud Expo, Manish Dixit, VP of Product and Engineering at Dice, discussed how Dice leverages data insights and tools to help both tech professionals and recruiters better understand how skills relate to each other and which skills are in high demand using interactive visualizations and salary indicator tools to maximize earning potential. Manish Dixit is VP of Product and Engineering at Dice. As the leader of the Product, Engineering and Data Sciences team at D...
Dec. 10, 2016 01:00 AM EST Reads: 1,277
"We're a cybersecurity firm that specializes in engineering security solutions both at the software and hardware level. Security cannot be an after-the-fact afterthought, which is what it's become," stated Richard Blech, Chief Executive Officer at Secure Channels, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 9, 2016 11:30 PM EST Reads: 1,163
In this strange new world where more and more power is drawn from business technology, companies are effectively straddling two paths on the road to innovation and transformation into digital enterprises. The first path is the heritage trail – with “legacy” technology forming the background. Here, extant technologies are transformed by core IT teams to provide more API-driven approaches. Legacy systems can restrict companies that are transitioning into digital enterprises. To truly become a lead...
Dec. 9, 2016 10:45 PM EST Reads: 582
Video experiences should be unique and exciting! But that doesn’t mean you need to patch all the pieces yourself. Users demand rich and engaging experiences and new ways to connect with you. But creating robust video applications at scale can be complicated, time-consuming and expensive. In his session at @ThingsExpo, Zohar Babin, Vice President of Platform, Ecosystem and Community at Kaltura, discussed how VPaaS enables you to move fast, creating scalable video experiences that reach your aud...
Dec. 9, 2016 10:00 PM EST Reads: 349
"Once customers get a year into their IoT deployments, they start to realize that they may have been shortsighted in the ways they built out their deployment and the key thing I see a lot of people looking at is - how can I take equipment data, pull it back in an IoT solution and show it in a dashboard," stated Dave McCarthy, Director of Products at Bsquare Corporation, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Dec. 9, 2016 09:30 PM EST Reads: 1,291
What happens when the different parts of a vehicle become smarter than the vehicle itself? As we move toward the era of smart everything, hundreds of entities in a vehicle that communicate with each other, the vehicle and external systems create a need for identity orchestration so that all entities work as a conglomerate. Much like an orchestra without a conductor, without the ability to secure, control, and connect the link between a vehicle’s head unit, devices, and systems and to manage the ...
Dec. 9, 2016 08:00 PM EST Reads: 1,048
IoT is rapidly changing the way enterprises are using data to improve business decision-making. In order to derive business value, organizations must unlock insights from the data gathered and then act on these. In their session at @ThingsExpo, Eric Hoffman, Vice President at EastBanc Technologies, and Peter Shashkin, Head of Development Department at EastBanc Technologies, discussed how one organization leveraged IoT, cloud technology and data analysis to improve customer experiences and effici...
Dec. 9, 2016 06:45 PM EST Reads: 5,152
Everyone knows that truly innovative companies learn as they go along, pushing boundaries in response to market changes and demands. What's more of a mystery is how to balance innovation on a fresh platform built from scratch with the legacy tech stack, product suite and customers that continue to serve as the business' foundation. In his General Session at 19th Cloud Expo, Michael Chambliss, Head of Engineering at ReadyTalk, discussed why and how ReadyTalk diverted from healthy revenue and mor...
Dec. 9, 2016 06:15 PM EST Reads: 1,773
The 20th International Cloud Expo has announced that its Call for Papers is open. Cloud Expo, to be held June 6-8, 2017, at the Javits Center in New York City, brings together Cloud Computing, Big Data, Internet of Things, DevOps, Containers, Microservices and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportunity. Submit your speaking proposal ...
Dec. 9, 2016 05:30 PM EST Reads: 2,384
The Internet of Things (IoT) promises to simplify and streamline our lives by automating routine tasks that distract us from our goals. This promise is based on the ubiquitous deployment of smart, connected devices that link everything from industrial control systems to automobiles to refrigerators. Unfortunately, comparatively few of the devices currently deployed have been developed with an eye toward security, and as the DDoS attacks of late October 2016 have demonstrated, this oversight can ...
Dec. 9, 2016 05:15 PM EST Reads: 1,488
You have great SaaS business app ideas. You want to turn your idea quickly into a functional and engaging proof of concept. You need to be able to modify it to meet customers' needs, and you need to deliver a complete and secure SaaS application. How could you achieve all the above and yet avoid unforeseen IT requirements that add unnecessary cost and complexity? You also want your app to be responsive in any device at any time. In his session at 19th Cloud Expo, Mark Allen, General Manager of...
Dec. 9, 2016 05:15 PM EST Reads: 1,905
As data explodes in quantity, importance and from new sources, the need for managing and protecting data residing across physical, virtual, and cloud environments grow with it. Managing data includes protecting it, indexing and classifying it for true, long-term management, compliance and E-Discovery. Commvault can ensure this with a single pane of glass solution – whether in a private cloud, a Service Provider delivered public cloud or a hybrid cloud environment – across the heterogeneous enter...
Dec. 9, 2016 04:45 PM EST Reads: 1,878
Bert Loomis was a visionary. This general session will highlight how Bert Loomis and people like him inspire us to build great things with small inventions. In their general session at 19th Cloud Expo, Harold Hannon, Architect at IBM Bluemix, and Michael O'Neill, Strategic Business Development at Nvidia, discussed the accelerating pace of AI development and how IBM Cloud and NVIDIA are partnering to bring AI capabilities to "every day," on-demand. They also reviewed two "free infrastructure" pr...
Dec. 9, 2016 04:45 PM EST Reads: 1,330