Sidebar

TechTip: SQL Server 2005 Linked Servers and Synonyms

SQL
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

Most SQL Server developers know the benefits that linked servers provide. Available since SQL Server 7.0, linked servers can use almost any ODBC or OLE DB data source to provide read/write connectivity to remote database objects. This provides developers with a powerful, easy-to-use tool for quickly writing code that treats remote database objects as though they are part of the local database.

If you need to catch up on all that linked servers can do—and learn how to create one—see the references at the end of this tip.

For review, consider this example that uses a linked server (using ODBC or OLE DB) named DB2SERVER to update remote table PURCHLINE on an iSeries from within T-SQL code:

UPDATE DB2SERVER.S105X6HM.DATALIB.PURCHLINE
   SET RCVQTY=@QTY, RCVDATE=@DATE
 WHERE PO=@PO
   AND POITEM=@POITEM

This Update is fairly typical in SQL with the exception that a four-part table name is employed. Specifically, for the iSeries using the IBM ODBC or OLE DB providers (IBMDA400 and IBMDASQL), the four-part table name is required as follows:

Linked Server Name.DB2 Relational Database Name.Schema Name.Table Name

Note that the relational database name, schema name, and table names must be all capitals!

As I explained in an earlier article, SQL Server 2005 can avoid using the four-part syntax in many cases by using the OPENQUERY function and the new EXEC AT statement. However, there are a few instances when the four-part table name syntax may be required to facilitate ease of writing code. One example would be writing an Update or Delete against data in a remote table that requires a subquery or join from a local SQL Server table. In this case, the four-part table name provides an easy way to include local and remote tables in a single statement:

UPDATE PURCHLINE
   SET RCVQTY=@QTY, RCVDATE=@DATE
  FROM DB2SERVER.S105X6HM.DATALIB.PURCHLINE AS PURCHLINE
  JOIN PurchaseReceipts On
       PurchaseReceipts.PONum=PurchLine.PO And
       PurchaseReceipts.ItemNum=PurchLine.POItem And
       PurchaseReceipts.ReceiptDate=Convert(VarChar(10),GetDate(),101)

This is very powerful integration functionality, but one drawback to this technique is that the linked server, relational database, and schema names all have to be hard-coded. Every time this remote table is referenced, these other three pieces of information go along with it. If this table is referenced in many T-SQL procedures or scripts, you'll have quite a maintenance chore if any of these three additional pieces of information change.

To help reduce this chore, SQL Server 2005 has introduced the concept of a "synonym." Somewhat similar to a DB2 alias name, the synonym simply provides an alternative name for referencing a remote table. (Actually, the synonym can be used to provide alternative names for other SQL Server objects as well. See the online help for more information.)

Using the familiar SQL CREATE/DROP syntax, a synonym is created or dropped as follows:

CREATE SYNONYM DB2PurchaseLine FOR DB2SERVER.S105X6HM.DATALIB.PURCHLINE;

DROP SYNONYM DB2PurchaseLine;

The messy reference to DB2SERVER.S105X6HM.DATALIB.PURCHLINE can now be reduced to DB2PurchaseLine. With the creation of the above synonym, the original Update statement is reduced to the following:

UPDATE DB2PurchaseLine
   SET RCVQTY=@QTY, RCVDATE=@DATE
 WHERE PO=@PO
   AND POITEM=@POITEM

The more complex sample statement is simplified as well:


UPDATE PURCHLINE

SET RCVQTY=PurchaseReceipts.Qty,
RCVDATE=PurchaseReceipts.ReceiptDate

  FROM DB2PurchaseLine AS PURCHLINE
  JOIN PurchaseReceipts On
       PurchaseReceipts.PONum=PurchLine.PO And
       PurchaseReceipts.ItemNum=PurchLine.POItem And
       PurchaseReceipts.ReceiptDate=Convert(VarChar(10),GetDate(),101)

Now, if you upgrade your iSeries/i5 and the relational database name of the system changes, you'll only have to DROP and CREATE each synonym instead of hunting through scripts, functions, and procedures. (ALTER SYNONYM doesn't appear to be available.)

Note that a synonym definition is created at the database level, not the server level. If you need to reuse a synonym among several databases, you may want to consider putting the synonym in a special "shared" database.

Once a synonym is created, it can be located under the Synonyms node of the SQL Server tree within the SQL Server management console. As with other objects, use the GRANT statement to assign permissions to appropriate users.

SQL Server 2000 and SQL Server 7.0 users can achieve the same thing using CREATE VIEW. The biggest difference between the techniques is that the VIEW definition is evaluated at creation time, whereas the synonym is created on the fly. If the remote table underlying the view changes, then the view may need to be re-created, whereas the synonym responds to changes on the fly.

In summary, synonyms make code cleaner by avoiding the use of the ugly four-part object name, and they ease maintenance chores by changing the reference to the linked server name, DB2 relational database name, or schema (library) name in one place.

As long as you're taking advantage of the rich integration features with linked servers, save yourself a few headaches and package your long remote-object references as synonyms.

References:
"DB2 Integration with SQL Server 2005, Part I: Linked Server Enhancements"
"Running Distributed Queries with SQL/400 and SQL Server 7.0" (AS/400 Network Expert, September/October 2000)
"Patch Those Leaky Interfaces"


Michael Sansoterra is a DBA for Broadway Systems in Grand Rapids, Michigan. He can be contacted at sqlsleuth@gmail.com.


BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

RESOURCE CENTER

  • WHITE PAPERS

  • WEBCAST

  • TRIAL SOFTWARE

  • White Paper: Node.js for Enterprise IBM i Modernization

    SB Profound WP 5539

    If your business is thinking about modernizing your legacy IBM i (also known as AS/400 or iSeries) applications, you will want to read this white paper first!

    Download this paper and learn how Node.js can ensure that you:
    - Modernize on-time and budget - no more lengthy, costly, disruptive app rewrites!
    - Retain your IBM i systems of record
    - Find and hire new development talent
    - Integrate new Node.js applications with your existing RPG, Java, .Net, and PHP apps
    - Extend your IBM i capabilties to include Watson API, Cloud, and Internet of Things


    Read Node.js for Enterprise IBM i Modernization Now!

     

  • Profound Logic Solution Guide

    SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation.
    Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects.
    The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the companyare not aligned with the current IT environment.

    Get your copy of this important guide today!

     

  • 2022 IBM i Marketplace Survey Results

    Fortra2022 marks the eighth edition of the IBM i Marketplace Survey Results. Each year, Fortra captures data on how businesses use the IBM i platform and the IT and cybersecurity initiatives it supports.

    Over the years, this survey has become a true industry benchmark, revealing to readers the trends that are shaping and driving the market and providing insight into what the future may bring for this technology.

  • Brunswick bowls a perfect 300 with LANSA!

    FortraBrunswick is the leader in bowling products, services, and industry expertise for the development and renovation of new and existing bowling centers and mixed-use recreation facilities across the entertainment industry. However, the lifeblood of Brunswick’s capital equipment business was running on a 15-year-old software application written in Visual Basic 6 (VB6) with a SQL Server back-end. The application was at the end of its life and needed to be replaced.
    With the help of Visual LANSA, they found an easy-to-use, long-term platform that enabled their team to collaborate, innovate, and integrate with existing systems and databases within a single platform.
    Read the case study to learn how they achieved success and increased the speed of development by 30% with Visual LANSA.

     

  • Progressive Web Apps: Create a Universal Experience Across All Devices

    LANSAProgressive Web Apps allow you to reach anyone, anywhere, and on any device with a single unified codebase. This means that your applications—regardless of browser, device, or platform—instantly become more reliable and consistent. They are the present and future of application development, and more and more businesses are catching on.
    Download this whitepaper and learn:

    • How PWAs support fast application development and streamline DevOps
    • How to give your business a competitive edge using PWAs
    • What makes progressive web apps so versatile, both online and offline

     

     

  • The Power of Coding in a Low-Code Solution

    LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed.
    Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

    • Discover the benefits of Low-code's quick application creation
    • Understand the differences in model-based and language-based Low-Code platforms
    • Explore the strengths of LANSA's Low-Code Solution to Low-Code’s biggest drawbacks

     

     

  • Why Migrate When You Can Modernize?

    LANSABusiness users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.
    In this white paper, you’ll learn how to think of these issues as opportunities rather than problems. We’ll explore motivations to migrate or modernize, their risks and considerations you should be aware of before embarking on a (migration or modernization) project.
    Lastly, we’ll discuss how modernizing IBM i applications with optimized business workflows, integration with other technologies and new mobile and web user interfaces will enable IT – and the business – to experience time-added value and much more.

     

  • UPDATED: Developer Kit: Making a Business Case for Modernization and Beyond

    Profound Logic Software, Inc.Having trouble getting management approval for modernization projects? The problem may be you're not speaking enough "business" to them.

    This Developer Kit provides you study-backed data and a ready-to-use business case template to help get your very next development project approved!

  • What to Do When Your AS/400 Talent Retires

    FortraIT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators is small.

    This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn:

    • Why IBM i skills depletion is a top concern
    • How leading organizations are coping
    • Where automation will make the biggest impact

     

  • Node.js on IBM i Webinar Series Pt. 2: Setting Up Your Development Tools

    Profound Logic Software, Inc.Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. In Part 2, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Attend this webinar to learn:

    • Different tools to develop Node.js applications on IBM i
    • Debugging Node.js
    • The basics of Git and tools to help those new to it
    • Using NodeRun.com as a pre-built development environment

     

     

  • Expert Tips for IBM i Security: Beyond the Basics

    SB PowerTech WC GenericIn this session, IBM i security expert Robin Tatam provides a quick recap of IBM i security basics and guides you through some advanced cybersecurity techniques that can help you take data protection to the next level. Robin will cover:

    • Reducing the risk posed by special authorities
    • Establishing object-level security
    • Overseeing user actions and data access

    Don't miss this chance to take your knowledge of IBM i security beyond the basics.

     

     

  • 5 IBM i Security Quick Wins

    SB PowerTech WC GenericIn today’s threat landscape, upper management is laser-focused on cybersecurity. You need to make progress in securing your systems—and make it fast.
    There’s no shortage of actions you could take, but what tactics will actually deliver the results you need? And how can you find a security strategy that fits your budget and time constraints?
    Join top IBM i security expert Robin Tatam as he outlines the five fastest and most impactful changes you can make to strengthen IBM i security this year.
    Your system didn’t become unsecure overnight and you won’t be able to turn it around overnight either. But quick wins are possible with IBM i security, and Robin Tatam will show you how to achieve them.

  • Security Bulletin: Malware Infection Discovered on IBM i Server!

    SB PowerTech WC GenericMalicious programs can bring entire businesses to their knees—and IBM i shops are not immune. It’s critical to grasp the true impact malware can have on IBM i and the network that connects to it. Attend this webinar to gain a thorough understanding of the relationships between:

    • Viruses, native objects, and the integrated file system (IFS)
    • Power Systems and Windows-based viruses and malware
    • PC-based anti-virus scanning versus native IBM i scanning

    There are a number of ways you can minimize your exposure to viruses. IBM i security expert Sandi Moore explains the facts, including how to ensure you're fully protected and compliant with regulations such as PCI.

     

     

  • Encryption on IBM i Simplified

    SB PowerTech WC GenericDB2 Field Procedures (FieldProcs) were introduced in IBM i 7.1 and have greatly simplified encryption, often without requiring any application changes. Now you can quickly encrypt sensitive data on the IBM i including PII, PCI, PHI data in your physical files and tables.
    Watch this webinar to learn how you can quickly implement encryption on the IBM i. During the webinar, security expert Robin Tatam will show you how to:

    • Use Field Procedures to automate encryption and decryption
    • Restrict and mask field level access by user or group
    • Meet compliance requirements with effective key management and audit trails

     

  • Lessons Learned from IBM i Cyber Attacks

    SB PowerTech WC GenericDespite the many options IBM has provided to protect your systems and data, many organizations still struggle to apply appropriate security controls.
    In this webinar, you'll get insight into how the criminals accessed these systems, the fallout from these attacks, and how the incidents could have been avoided by following security best practices.

    • Learn which security gaps cyber criminals love most
    • Find out how other IBM i organizations have fallen victim
    • Get the details on policies and processes you can implement to protect your organization, even when staff works from home

    You will learn the steps you can take to avoid the mistakes made in these examples, as well as other inadequate and misconfigured settings that put businesses at risk.

     

     

  • The Power of Coding in a Low-Code Solution

    SB PowerTech WC GenericWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed.
    Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

    • Discover the benefits of Low-code's quick application creation
    • Understand the differences in model-based and language-based Low-Code platforms
    • Explore the strengths of LANSA's Low-Code Solution to Low-Code’s biggest drawbacks

     

     

  • Node Webinar Series Pt. 1: The World of Node.js on IBM i

    SB Profound WC GenericHave you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.
    Part 1 will teach you what Node.js is, why it's a great option for IBM i shops, and how to take advantage of the ecosystem surrounding Node.
    In addition to background information, our Director of Product Development Scott Klement will demonstrate applications that take advantage of the Node Package Manager (npm).
    Watch Now.

  • The Biggest Mistakes in IBM i Security

    SB Profound WC Generic The Biggest Mistakes in IBM i Security
    Here’s the harsh reality: cybersecurity pros have to get their jobs right every single day, while an attacker only has to succeed once to do incredible damage.
    Whether that’s thousands of exposed records, millions of dollars in fines and legal fees, or diminished share value, it’s easy to judge organizations that fall victim. IBM i enjoys an enviable reputation for security, but no system is impervious to mistakes.
    Join this webinar to learn about the biggest errors made when securing a Power Systems server.
    This knowledge is critical for ensuring integrity of your application data and preventing you from becoming the next Equifax. It’s also essential for complying with all formal regulations, including SOX, PCI, GDPR, and HIPAA
    Watch Now.

  • Comply in 5! Well, actually UNDER 5 minutes!!

    SB CYBRA PPL 5382

    TRY the one package that solves all your document design and printing challenges on all your platforms.

    Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product.

    Request your trial now!

  • Backup and Recovery on IBM i: Your Strategy for the Unexpected

    FortraRobot automates the routine tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:
    - Simplified backup procedures
    - Easy data encryption
    - Save media management
    - Guided restoration
    - Seamless product integration
    Make sure your data survives when catastrophe hits. Try the Robot Backup and Recovery Solution FREE for 30 days.

  • Manage IBM i Messages by Exception with Robot

    SB HelpSystems SC 5413Managing messages on your IBM i can be more than a full-time job if you have to do it manually. How can you be sure you won’t miss important system events?
    Automate your message center with the Robot Message Management Solution. Key features include:
    - Automated message management
    - Tailored notifications and automatic escalation
    - System-wide control of your IBM i partitions
    - Two-way system notifications from your mobile device
    - Seamless product integration
    Try the Robot Message Management Solution FREE for 30 days.

  • Easiest Way to Save Money? Stop Printing IBM i Reports

    FortraRobot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing.
    Manage your reports with the Robot Report Management Solution. Key features include:

    - Automated report distribution
    - View online without delay
    - Browser interface to make notes
    - Custom retention capabilities
    - Seamless product integration
    Rerun another report? Never again. Try the Robot Report Management Solution FREE for 30 days.

  • Hassle-Free IBM i Operations around the Clock

    SB HelpSystems SC 5413For over 30 years, Robot has been a leader in systems management for IBM i.
    Manage your job schedule with the Robot Job Scheduling Solution. Key features include:
    - Automated batch, interactive, and cross-platform scheduling
    - Event-driven dependency processing
    - Centralized monitoring and reporting
    - Audit log and ready-to-use reports
    - Seamless product integration
    Scale your software, not your staff. Try the Robot Job Scheduling Solution FREE for 30 days.