|By Randy Smith||
|June 22, 2000 12:00 AM EDT||
First, a confession: I'm a Microsoft SQL Server plebe. Oh, sure, I've written plenty of SQL commands for Access, Foxpro and even an occasional Oracle database, but the needs of more than one client called out for me to tackle SQL Server.
Have you traveled down this road yet? Maybe you've tried to set up an OLEDB connection only to be stymied by the terminology, or perhaps connection failures stopped you? You're not alone. I searched through multiple books, Books Online and the Allaire Forums without success. Judging from the comments of others I met in the forums, setting up an OLEDB connection has caused quite a few programmers to lose their sanity.
Like many ColdFusion programmers, I would normally just turn to ODBC links to handle the connection for me. When I moved into SQL Server, though, I decided to upgrade my skill with the CFQUERY command and take advantage of the multiple databases that the design of SQL Server allows (much more so than Access does). I also wanted to reduce the number of Data Source Names (DSNs) that I had to rely on and remember.
You may already know this, but you can't code an ODBC DSN to use a SQL Server database, other than the default database associated with that DSN. Consider for instance:
<cfquery datasource="vipclient" dbname="pubs" dbtype="ODBC" username="myid"
password="mypsw">SELECT * FROM tblSecurity</cfquery>
This will work just fine if your ODBC link is, indeed, pointing at the "pubs" database in setup and all other items (like username and password) are correct. What if we change the database name, however, as in this example:
<cfquery datasource="vipclient" dbname="personnel" dbtype="ODBC" username="myid"
password="mypsw">SELECT * FROM tblHumans</cfquery>
Now your code will crash with an "Invalid object name tblHumans'" error. Think database security is the problem? Because your ODBC link is set to the "pubs" database, if you change the username and password to the "personnel" database, you'll get a different error: "Cannot open database requested."
Cue the Knight In Shining Armor...
OLEDB, on the other hand, will handle this task with ease. With one OLEDB link and the username and password for each database, you can access all of your SQL Server databases on that server! Unfortunately, you need to jump a hurdle and squish a bug to get it working properly.
Kicking and screaming, I turned a few more hairs gray as I fought to get OLEDB working on my development LAN, a Microsoft Small Business Server 4.5, IIS 4.0 intranet running single-user ColdFusion Server 4.5 and SQL Server 7.0. After I figured out the process, I assisted my ISP in successfully establishing an OLEDB link on their CF Server 4.5. Now let's get your connection working.
Step by Step
To follow along, you'll need access to the ColdFusion Server Administrator. You should already have SQL Server running with at least one database containing at least one table. Finally, make sure you know the username and password for that SQL Server database.
In the ColdFusion Administrator, select OLE DB from the menu. The first input form you receive looks simple enough (see Figure 1), asking only for a DSN and a Provider. After entering the DSN you want to refer to this connection by, make sure "SQLOLEDB" is listed in the provider box and click the Add button.
Problem No. 1
The next form you receive, seen here in Figure 2, is the one that causes the pain. It's unclear just what is being asked for as inputs and there's no useful help information anywhere to be found.
Note: If I may interject here (and do please listen up, Allaire!)....When you have a form that is entirely utilitarian, please put a description of the terms below the form and include both a description of the field and an example of what should go in that field.
Part of the problem is that this form has a bug in it, if I may use that term somewhat loosely. While the DSN carried over fine, the Provider field didn't. The Provider field should have been prefilled in for you with "SQLOLEDB," the option you chose in the first form.
That one piece of information, that little bug, is the first of two obstacles that stand in the way of aspiring OLEDB administrators. Finish filling out this form with a description (not required, but useful for resolving short-term memory lapses), the name of the SQL Server and the database you'll be using the most often.
Problem No. 2
Before you press Update, however, we need to move into the CF Settings area for a moment to resolve the second obstacle: the username and password. Settle down, you security purists; I'll make things right in a bit. Click on the "CF Settings" button to expand the form, then refer to Figure 3.
Enter the username and password to access the SQL Server database, then press the "Update" button. You should have a "Verified" indicator on the right side of your new connection when your list of OLEDB DSNs is displayed. If you want to be absolutely sure that this connection is working, click on the Verify link. Congratulations! You've successfully established an OLEDB link!
Don't Compromise Security!
Feeling a little nervous about having your username and password hard-coded in the connection? You should be. Anyone can easily get access to your database because of this, so let's fix it. Realize, though, that this was a necessary step for us to ensure that our connection was working. You could have left it off and used a <CFQUERY> command to test the link, but as long as we're here, why not make sure?
Return to the list of OLEDB DSNs if you're not there already, then click on your DSN to edit it. Click again on the "CF Settings" button and remove the username and password, then press the "Update" button.
Now when you return to your OLEDB DSN list, you'll see that your connection has failed (see Figure 4). This isn't a problem! It simply means that CF Administrator couldn't verify that the link worked because SQL Server's security is preventing access. This is a good thing.
Your OLEDB connection is finished and ready for use. Remember to supply the username and password whenever you submit a <CFQUERY> using the OLEDB DSN. I would recommend that you keep the DSN, username and password in your Application.cfm file as variables and use the variable names in your CFQUERYs.
I first got the idea to pursue OLE- DB from Ben Forta. Ben had used OLEDB connections, of course, but he admitted that setup could be less painful. When I informed him that I'd not only figured out the trick to get OLEDB going but that I would be submitting this article on it for publication as well, he suggested that I run some benchmarks to show speed differences between ODBC and OLEDB.
Well, I did run some comparisons...but my MBA prevents me from reporting those statistics because I didn't adhere to any form of scientific method and time prevents me from going back and doing it all over again! I did find that OLEDB was a little faster than ODBC to the same SQL Server database. Specifying the database name instead of relying on the OLEDB connection to fill in the default database also seemed to speed it up. Perhaps another day we can pursue speed, but I think that's fodder for a new article and outside the scope of this one.
Speed issues aside, the primary reason that I wanted to get OLEDB up and running was to have a single DSN that could be used to access multiple databases - and OLEDB succeeds in that respect. Now that the mystery is cleared up and the Administrator bug is identified, I'd be willing to bet the OLEDB flood-gates will open to more flexible SQL Server access for a great number of CF programmers.
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