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Linked server sql statements

Klaas Deforche — Fri, 23 Jul 2010 16:29:55 +0000

Hi all, hope you are well.

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.

query = strfmt("select top 1 * from sys.servers where name = '%1'", this.parmServer());

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

query = strfmt("EXEC sp_addLinkedServer @server = '%1', @srvproduct=N'SQL Server'", this.parmServer());

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

query = strfmt("sp_addlinkedsrvlogin @rmtsrvname = '%1' ,@useself = FALSE, @locallogin = NULL, @rmtuser = '%2', @rmtpassword = '%3'",
this.parmServer(),
this.parmUsername(),
this.parmPassword());

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

query = strfmt("EXEC sp_dropserver '%1', 'droplogins'", this.parmServer());

Executing direct SQL statements

Klaas Deforche — Mon, 21 Jun 2010 16:35:22 +0000

Hi everyone,

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:

public static server void main(Args _args)
{
Connection connection;
Statement statement;
str query;
Resultset resultSet;
;

// create connection object
connection = new Connection();

// create statement
statement = connection.createStatement();

// Set the SQL statement
query = 'select name from CustTable';

// assert SQL statement execute permission
new SqlStatementExecutePermission(query).assert();

// when the query returns result,
// loop all results for processing
//BP Deviation documented
resultSet = statement.executeQuery(query);

while(resultSet.next())
{
// do something with the result
info(resultSet.getString(1));
}

// limit the scope of the assert call
CodeAccessPermission::revertAssert();
}

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:

public static server void main(Args _args)
{
Connection connection;
Statement statement;
str query;
;

// create connection object
connection = new Connection();

// create statement
statement = connection.createStatement();

// Set the SQL statement
query = "insert into CustTable (AccountNum, Name, RecId) values ('demo', 'demo', 2)";

// assert SQL statement execute permission
new SqlStatementExecutePermission(query).assert();

//BP Deviation documented
statement.executeUpdate(query);

// limit the scope of the assert call
CodeAccessPermission::revertAssert();
}

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:

public static server void main(Args _args)
{
Statement statement;
str query;
Resultset resultSet;
LoginProperty loginProperty;
OdbcConnection odbcConnection;
;

loginProperty = new LoginProperty();
loginProperty.setDSN('YOURDSN');

odbcConnection = new OdbcConnection(loginProperty);

// Create new Statement instance
statement =odbcConnection.CreateStatement();

// Set the SQL statement
query = 'select name from CustTable';

// assert SQL statement execute permission
new SqlStatementExecutePermission(query).assert();

// when the query returns result,
// loop all results for processing by handler
//BP Deviation documented
resultSet = statement.executeQuery(query);

while(resultSet.next())
{
// do something with the result
info(resultSet.getString(1));
}

// limit the scope of the assert call
CodeAccessPermission::revertAssert();
}

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:

public static server void main(Args _args)
{
Statement statement;
str query;
LoginProperty loginProperty;
OdbcConnection odbcConnection;
;

loginProperty = new LoginProperty();
loginProperty.setDSN('YOURDSN');

odbcConnection = new OdbcConnection(loginProperty);

// Create new Statement instance
statement =odbcConnection.CreateStatement();

// Set the SQL statement
query = "insert into CustTable (AccountNum, Name, RecId) values ('demo', 'demo', 2)";

// assert SQL statement execute permission
new SqlStatementExecutePermission(query).assert();

// when the query returns result,
// loop all results for processing by handler
//BP Deviation documented
statement.executeUpdate(query);

// limit the scope of the assert call
CodeAccessPermission::revertAssert();
}

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

Normalization dilemma

Klaas Deforche — Fri, 28 May 2010 22:42:49 +0000

Hi all!

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?

Remove duplicate key entry from a table

Klaas Deforche — Mon, 12 Apr 2010 16:12:08 +0000

Sometimes, you can’t synchronize a table because is contains duplicate records. This can occur when you change field lengths on a extended data type for example.

I’ve seen people write huge SQL statements, and even jobs that create these SQL statements to remove these duplicates from a table, but there’s actually a easy way to do this in AX.

Say you have a table KLFTestDuplicates that contains duplicates, then simple run the following job to remove them.

static void KLFRemoveDuplicates(Args _args)
{
Set fieldSet = new set(Types::Integer);

DictIndex dictIndex = new DictIndex(
tablenum(KLFTestDuplicates),
indexnum(KLFTestDuplicates, AUniqueIdx));
int i;
;

if(dictIndex.numberOfFields())
{
for(i=1;i<=dictIndex.numberOfFields();i++)
{
fieldSet.add(dictIndex.field(i));
}

ReleaseUpdateDB::indexAllowDup(dictIndex);

ReleaseUpdateDB::deleteDuplicatesUsingIds(tablenum(KLFTestDuplicates), 0, fieldSet);

ReleaseUpdateDB::indexAllowNoDup(dictIndex);
}

info("done");
}

Remember: this is useful when developing and testing, but it will remove data from you database, so use it with caution.

Check what application and database you are connected to

Klaas Deforche — Mon, 04 Jan 2010 18:27:52 +0000

If you want a quick way to check to what database and application folder you are connected, you can use the ‘Upgrade checklist’ form:

Administration – Setup – System – Checklists – Upgrade checklist.

It shows you:
- Database server
- Database name
- Application folder
- Layers in the application

Upgrade Checklist