Sql Statements in C/AL – Part 1 : Select

There is no possibility to read data from an external database with standard c/al. Best way to do that till NAV version 2009 is using ADO. With Nav vs. 2013 upwards you can use .Net classes.
The following code can be used to read data from a given, external database.

// local variables
ADOConnection	  Automation	'Microsoft ActiveX Data Objects 2.8 Library'.Connection	
ADOCommand	  Automation	'Microsoft ActiveX Data Objects 2.8 Library'.Command	
ADOParameter	  Automation	'Microsoft ActiveX Data Objects 2.8 Library'.Parameter	
ADORecSet	  Automation	'Microsoft ActiveX Data Objects 2.8 Library'.Recordset	
adoField	  Automation	'Microsoft ActiveX Data Objects 2.8 Library'.Field	
connString	  Text		1024
activeConnection  Variant		
salesLineStr	  Text		1024
idx		  Integer		
adoValue	  Variant		
adoType		  Integer		

// the code
// replace the server ip and the ext. databasename with your values
ReadFromExternalDatabase()
connString := 'Driver={SQL Server};Server=127.0.0.1;Database=Cronus600';
CREATE(ADOConnection);
ADOConnection.ConnectionString(connString);
ADOConnection.Open;
// convert ADO Connection to Variant
activeConnection := ADOConnection;

CREATE(ADOCommand);
ADOCommand.ActiveConnection := activeConnection;
ADOCommand.CommandType := 1; // type is sql statement
// sample statement: read first record from table sales line
ADOCommand.CommandText := 'select top 1 * from [CRONUS AG$Sales Line]';
ADOCommand.CommandTimeout := 100;

CREATE(ADORecSet);
ADORecSet := ADOCommand.Execute;
ADORecSet.MoveFirst;  // goto first record
FOR idx := 1 TO ADORecSet.Fields.Count - 1 DO BEGIN
  adoField := ADORecSet.Fields.Item(idx);
  adoType := adoField.Type;
  IF adoType <> 131 THEN  // ado type numeric must be converted
    adoValue := adoField.Value
  ELSE
    adoValue := GetFieldValue(adoField);
  IF (adoField.Type <> 13) THEN  // ado type 13 = Unknown
    // gets the value with index idx of the resulting record
    salesLineStr := salesLineStr + FORMAT(adoValue);
  salesLineStr := salesLineStr + ';';
END;
MESSAGE(salesLineStr);

ADORecSet.Close;
ADOConnection.Close;
CLEARALL;

GetFieldValue(adoField : 'Microsoft ActiveX Data Objects 2.8 Library'.Field) : Text
// local variables
// ADOStream	  Automation	'Microsoft ActiveX Data Objects 2.8 Library'.Stream	
// RetVal	  Text		
ADOStream.Open;
ADOStream.WriteText(adoField.Value);
ADOStream.Position:= 0;
RetVal:= ADOStream.ReadText;
ADOStream.Close;
exit(RetVal);

helpful links:

http://www.w3schools.com/asp/ado_ref_connection.asp

http://www.w3schools.com/asp/ado_ref_command.asp

http://www.w3schools.com/asp/prop_comm_commandtype.asp#commandtypeenum