Home > Articles

This chapter is from the book

Connecting to a Database Server

After you define a data source, you are ready to connect to it. You can use these methods to access server data:

  • Link to tables residing on the server

  • Link to views residing on the server

  • Use pass-through queries to send SQL statements directly to the server

  • Use VBA code to open the server tables directly

  • Create an Access Data Project (with this option, you do not define an ODBC data source)

Working with Linked Tables

The easiest method of accessing data on the server is to link to the external tables. These linked tables act almost exactly like native Access tables. When you link to remote tables, Access analyzes the fields and indexes contained in the tables so that it can achieve optimal performance. It is important to relink the tables if the structures of the remote tables change. You can use the following techniques to link to external tables:

  • Linking to external tables via the user interface

  • Linking to external tables using code

Linking to Views Rather Than Tables

Views on a database server are similar to Access queries. Views provide a form of security by limiting which rows and columns a user can see. You give access to the view rather than directly to the underlying table. By default, views are not updateable. You can make a view updatable by including all the fields that compose the primary key in the view and building a unique index on the primary key. You can create views in one of three ways:

  • Using the SQL Server Enterprise Manager for SQL 7.0 or SQL 2000 (or the equivalent option for your back-end database server)

  • Using the Create View statement in Access

  • Using the View tab of an ADP file

NOTE

Chapter 11, "Developing an MDB Client/Server Application with Linked Tables," covers the process of working with linked tables in detail.

Using Pass-Through Queries

Ordinarily, store and execute a query in Access, even if it is running on remote data, Access compiles and optimizes the query. In many cases, this is exactly what you want. On other occasions, however, it might be preferable for you to execute a pass-through query because these queries are not analyzed by Access's Jet Engine. These queries are passed directly to the server, and this reduces the time Jet needs to analyze the query and enables you to pass server-specific syntax to the back end. Furthermore, pass-through queries can log informational messages returned by the server. Finally, bulk update, delete, and append queries are faster using pass-through queries than they are using Access action queries based on remote tables.

Pass-through queries do have their downside. They always return a snapshot, rendering them not updatable. You also must know the exact syntax the server requires, and you must type the statement into the Query window instead of painting it graphically. Finally, you cannot parameterize a query so that it prompts the user for a value.

Creating a Pass-Through Query in an MDB File Using the User Interface

To create a pass-through query, you can build the query in the Access query builder. Choose Query, SQL Specific, Pass-Through. You are presented with a text-editing window where you can enter the query statement. The SQL statement that you enter must be in the SQL flavor specific to your back end.

Executing a Pass-Through Query Using Code

You also can perform a pass-through query by using VBA code. In fact, you must create the pass-through query by using VBA code if you want the query to contain parameters that you will pass to the server.

NOTE

Chapter 11 covers the process of working with pass-through queries in detail.

Executing and Creating Stored Procedures

You can execute stored procedures on a back-end database server. A stored procedure is similar to a query or program stored on the back end, and it performs some action.

Executing a Stored Procedure

An example is the SQL Server 2000 stored procedure named sp_columns. This stored procedure returns information on the fields in a particular table. Figure 3.22 shows how you would execute the sp_columns stored procedure from the Query Design window. You simply type the name of the stored procedure and any parameters it must receive. Take a good look at the Query Properties window shown in Figure 3.22. If you enter a valid ODBC connect string, the user is not prompted to log on at runtime. The Return Records property is another important property. In this case, you want to set the value of the property to Yes so that you can see the results of the stored procedure. If the stored procedure does not return records, it is important to set this property to No. Otherwise, you receive an error message indicating that no rows were returned. Figure 3.23 shows the results of running the stored procedure.

Figure 3.22Figure 3.22 If you enter a valid ODBC connect string in the Properties window, Access does not prompt the user to log in at runtime.

Figure 3.23Figure 3.23 The result of running the sp_columns stored procedure.

Creating a Stored Procedure

If your application is an ADP file, you can create stored procedures directly from the Access environment. If your application is an MDB file, you can create a stored procedure using a pass-through query. In either case, you can create a stored procedure using the SQL Server Query Analyzer or the SQL Server Enterprise Manager.

NOTE

Chapter 8, "Designing SQL Server Stored Procedures, User-Defined Functions, and Triggers," and Chapter 11 cover the process of creating and working with stored procedures in detail.

Using a Microsoft Access Data Project to Access Client/Server Data

As mentioned earlier in this chapter, Access projects (ADP files) enable you to work with SQL Server databases without loading the Microsoft Jet Engine. Access projects have the following advantages over the other methods of accessing client/server data covered in this chapter:

  • They provide you direct access to a Microsoft SQL Server database.

  • You can easily create and modify SQL Server tables, views, database diagrams, and stored procedures all from the Access development environment.

  • You can build forms, reports, data access pages, and modules that access SQL Server data, without involving Jet.

  • Fewer resources are required on the client side.

  • The server is responsible for all query processing.

  • You can access functionality not available when accessing ODBC via Jet.

  • You can execute asynchronous queries. This means that you don't have to wait for a query to complete execution before you begin another operation.

  • You can perform batch updates. This means that you can cache changes locally and then submit them to the server as a batch.

  • You can run queries that return multiple resultsets.

  • You easily can limit the number of records returned in a resultset.

  • You easily can monitor messages and errors generated by the remote data source.

The disadvantages of Access Data Project files follow:

  • You cannot create local tables.

  • You cannot create local queries.

  • There is a learning curve associated with the process of becoming proficient in working with ADP files.

  • The process of creating tables, views, database diagrams, and stored procedures involves a learning curve.

NOTE

Chapter 12, "Developing an ADP Application," covers the process of working with ADP files in detail.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020