Some time ago, I talked about executing direct sql statements, and now I want to share some sql statements that I used to manage linked server connections.

What follows are 4 sql statements that allow you to add en remove linked servers on a database at runtime.

Some assumptions:
- There is a str variable named “query” that will contain the query
- there is a parm method on the class that return the sql server (“server” or “server\instance”)
- there is a parm method that returns a username
- there is a parm method that returns a password

Check if linked server exist
First check if the linked server doesn’t exist yet, or you will get an error when you try to add one that already exists.

Add linked server
When the linked server doesn’t exist, add it.

Add linked server login
Optionally, you can add a login that will be used to connect to the linked server.

Remove linked server
Optionally, you can remove the linked server.

There seems to be a problem with the recently released RU5 for Dynamics AX 2009 SP1.
Dynamics AX clients are supposed to be backwards compatible, so you can always use the latest client, even if you want to connect to an application with a lower version (e.g. AX 2009 RU4 client to AX 2009 RU3 application).

But when I tried to connect to an AX 2009 RU3 application (5.0.1500.1313) after I updated my client to RU5 (5.0.1500.2985), it didn’t work.
Dynamics AX only shows the first record in the forms when you use that combination, as you can see in the screenshot below.

Roll up 5

When you connect using a RU4 client (or RU3), there is no problem at all.

Roll up 4

You can uninstall a hotfix rollup from the Add/Remove software screen in the windows control panel if you want to.

I prefer to duplicate the client folder each time I upgrade it so I have all client versions available.
Just fire up bin\ax32.exe for the version you want and you good to go :-).

The only problem with the NormalResource property is that it asks for an integer. But how do you know what integer the icon has that you want to use?

You can use this form:

Depending on what AX version you are using, the name of the form is different:
Dynamics AX 4: form Tutorial_Resources
Dynamics AX 2009: form SysImageResources

For some reason, Microsoft changed the name of that form in AX 2009, and because I started working with AX version 4.0, I always forget the name of that new form :-).

Update: in AX 2009, you can also open this form in the AX menu; click Tools – Development Tools – Embedded resources.

Today I want to talk about executing SQL statements in X++ on both the AX database and external databases. This is something probably every AX developer will have to do at some point.

You’ll want to do this for many reasons; to execute stored procedures, to improve performance, to get data from an external database, and so on.

I will provide samples for two classes:
- Connection (Execute SQL statement on current AX database)
- ODBCConnection (Execute SQL statement on external database)

I will not cover the ADO connection (CCADOConnection class), because it doesn’t work when you run it on server (or in batch), and I don’t like that. If you do, try to convince me ;-).

Executing direct SQL on the current AX database

When you execute a SQL statement, there are two options:
- either you did a select and you expect a result to be returned
- or you did insert/update/delete and you don’t expect a result.

The first sample is for a SQL statement that returns a result:

Note: this is a main method, put it in a class. Also note that it has to run on server.

Now if you do an update/delete/insert, you will want to do something like this:

You can find more info about the executeQuery() and executeUpdate() methods on msdn:
Statement Class

Executing direct SQL on an external database using ODBC

Again, we have to differentiate between queries that return a result and those that don’t.

The following code sample retrieves records from an external database and processes the result:

As you can see, the code is pretty similar. The main difference is that we are using ODBC classes, including the LoginProperty class.

In this example, I use a DSN (Data Source Name) that I configured on the AOS server. The DSN contains a reference to the server and database you want to connect to, and also what user credentials should be used to connect to the database. This is a lot safer than storing them in AX.
If you don’t know how to create a DSN, there are plenty of tutorials on the web.

To update/delete/update, the code is more or less the same:

If you feel that something is missing in these examples, just ask.

Just to announce that this blog is now part of the Dynamics AX Community.

You can read all about it in this warm welcome message on the Microsoft Dynamics AX Community Team blog.

While you are at it, create a profile (if you don’t already have one), because with the newsgroups closing any time now, the Dynamics AX Community is the place to be for all your community needs.

I have a dilemma, and would like your opinions.
The situation is that I want to add fields to an existing table (say InventTable)

What would you prefer:

So the question is, should I add new fields to the table (option one), or should I create a new table with the fields and link to it. (option 2)

Normally, option 1 is the standard way of adding extra fields to a table, but option 2 has a few advantages:

• You don’t need to modify the existing table
• You’ll have less trouble with these fields when you have to upgrade AX
• It will be easier to deploy your modifications in an AX environment that already contains modifications to the table

There are also a few disadvantages I can think of:

• You have to join 2 tables to get the data from the new fields
• You can’t add the new fields to fields groups on the main table (InventTable in this example)
• On forms, you will have to add a new data source, or add display fields

I would certainly go for option 1 when doing customizations for a customer, but would consider option 2 for product development. I’m in doubt. How about you?

Some time ago, I talked about the ‘construct’ pattern that is use a lot in AX. Although I use it often, it’s not perfect because it violates some best practices. (Also, you could end up with a large class hierarchy of classes that extend each other, but I’ll discuss that in an other post.)

First off, know that you can change the compiler level and the best practices the compiler checks.
To do this, compile something so the compiler output window pops up. Then click the setup button, and adjust the settings.
I used compiler level 4 and enabled all BP checks for this example.

So, let create a simple class. This class will simply print information of an InventTable record to the screen.

1. ClassDeclaration
When we think about this class a bit, we immediately realize that we need to declare an InventTable record as a member of out class:

Also note that I added documentation to this method. I will do so for other methods too. When you don’t, you’ll get a BP deviation warning.

2. Parm method
One of the things that are important (or at least I find important), is using parm methods for your class variables. So, let’s create one:

3. New method
You should never write code in the new method, or add parameters to it. On the contrary, you should always set this method to protected, and use a static construct() or a static new…() method instead.

4. Run method
The run method will be our method that contains our logic. Here, we print info to the screen

Note that we are using the parm method instead of directly accessing the variable.

5. Construct method
Because the new method is now protected, we will need a contruct method to be able to create an instance of this class.

When a class doesn’t need parameters, you can leave out the ‘private’, but now, it is private because we plan on creating a new…() method that contains parameters. A construct method shouldn’t contain parameters, and should only be used to create a new instance of your class. It is also the only place in your application where you can call the new() method of your class.

6. New…() method
As said earlier, because we need a parameter (an InventTable record), we use a new…() instead of the construct method to create an instance of our class. I will name it newFromInventTable() based on the parameter it has.
In this method, we call the contruct() method to create an instance (instead of new()), set the parm method from the parameter and return the object.

You could also create an init() method that initializes you class (we don’t need initialization now). The init() method should return a boolean if initialization can go wrong, so you can throw an error.
It would look like this:

Remember to create a label for the text string, or you will get a best practice error.

7. Main method
Now, all we need more is a main method, so this class is runable (by pressing F5 or as a menu item).

Normally, you will get the record from the args object, but for demo purposes, I added the ‘select firstonly’ so you can run the class by pressing F5. As you can see, the new…() method is used to create an instance of the class, and then the run method is called.

There you go, you now have a best practice deviation free class!

8. Using the class
Using the class as a menu item or in code couldn’t be easier.

You can drag/drop the class to the action menu item node in the AOT to create a menu item, and you will be able to use it on any form with the inventTable datasource.

From code, you can simple write this line (assuming there is a variable called inventTable):

Conclusion:
When writing code that doesn’t contain any best practice deviations (especially when checking them all on compiler level 4), you quickly end up with a lot of methods in your class and wondering if the effort is worth it. It can be a bit painful to get your code best practice deviation free.

However, you’ll also realise that following the best practices has its advantages. Your code will be cleaner, easier to understand, easier to debug because of the parm, constuct and run methods, less subject to change, contain less errors and your class will be used in the way you intended when you wrote it.

More info on MSDN:
Best practices for constructors

Illegal property Value

This is because on your table, the property PrimaryIndex is set to the index you are trying to change.

It’s a shame, because I visit the AX development group using the web based news reader daily, and I will miss it.

Where will we go now? To the Dynamics Forums?

It splits an input text file into smaller files.
As there is one comment line for every line of code (almost), I’m sure you’ll figure it out :-).