BDE Alias Analyser
But first of all, let's consider my BDE Alias analyser. The purpose of this little tool (which can be seen in Listing 1), is to walk through all tables in a given alias, and produce some detailed information for each of these tables. The helpful method that gives us all tablenames for a given alias can be obtained by calling the GetTableNames method from an active Session component (very BDE specific, indeed), as follows: Once we have a list of TableNames, we need to use those to open specific TTable components (using both the given AliasName and TableName) and list relevant information for fields, such as Name, Type and whether or not a value is required. We can also use the IndexDefs to list the known indices (like the primary index).

  program analias;
  {$APPTYPE CONSOLE}
  uses
    Classes, DB, DBTables;
  var
    i,j: Integer;
    TableNames: TStringList;
  begin
    TableNames := TStringList.Create;
    with TSession.Create(nil) do
    try
      AutoSessionName := True;
      GetTableNames(ParamStr(1), '', True, False, TableNames);
    finally
      Free
    end;
    with TTable.Create(nil) do
    try
      DatabaseName := ParamStr(1);
      for j:=0 to Pred(TableNames.Count) do
      begin
        writeln;
        TableName := TableNames[j];
        Open;
        writeln(TableNames[j],' ',RecordCount:4);
        writeln('<TABLE BORDER=1>');
        writeln('<TR><TD BGCOLOR=FFFFFF>Field</TD>'+
                    '<TD BGCOLOR=FFFFFF>Name</TD>'+
                    '<TD BGCOLOR=FFFFFF>Type</TD>'+
                    '<TD BGCOLOR=FFFFFF>Req</TD></TR>');
        for i:=0 to Pred(FieldCount) do
        begin
          write('<TR><TD>',i,'</TD><TD>');
          write(Fields[i].DisplayName,'</TD><TD>');
          write(FieldDefs[i].FieldClass.ClassName);
          if FieldDefs[i].DataType = ftString then
            write('[',FieldDefs[i].Size,']');
          write('</TD><TD>');
          if FieldDefs[i].Required then write('Yes');
          writeln('</TD></TR>');
        end;
        writeln('</TABLE>');
        writeln('<BR>');
        IndexDefs.Update;
        if IndexDefs.Count > 0 then
        begin
          writeln('<TABLE BORDER=1>');
          writeln('<TR><TD BGCOLOR=FFFFFF>Index</TD>'+
                      '<TD BGCOLOR=FFFFFF>Name</TD>'+
                      '<TD BGCOLOR=FFFFFF>Fields</TD></TR>')
        end;
        for i:=0 to Pred(IndexDefs.Count) do
        begin
          write('<TR><TD>',i,'</TD><TD>');
          write(IndexDefs[i].DisplayName,'</TD><TD>');
          write(IndexDefs[i].Fields);
          writeln('</TD></TR>')
        end;
        writeln('</TABLE>');
        writeln('<P>');
        Close
      end
    finally
      Free
    end
  end.

Note that the code from Listing 1. uses HTML tags as delimiter between the different values (or columns). This is done so I can import the resulting file inside Windows, and convert the text to a Winword table, which results in a nice and readable report (but I could have used tabs as well). As an example, the table BIOLIFE.DB from Alias DBDEMOS is analysed and reported as follows:

biolife.db 28    

Field	Name	Type	Req
0	Species No	TFloatField
1	Category	TStringField[15]
2	Common_Name	TStringField[30]
3	Species Name	TStringField[40]
4	Length (cm)	TFloatField
5	Length_In	TFloatField
6	Notes	TMemoField
7	Graphic	TGraphicField

  

Index	Name	Fields
0		Species No

By the way, you can extend the code from listing 1. with additional features that can report even more information, like range (min value, max value), etc. but the information printed above is usually enough for my first analysis anyway.

dbExpress Analyser
As you probably know: Kylix is shipping (I recently received my copy of Kylix Server Developer edition), and - what you may or may not know - Kylix is not using the BDE, but rather uses something called dbExpress for data access. And Delphi 6 will be using BDE as well as dbExpress, so most of what I'm saying in the remainder of this article will probably also work with the forthcoming Delphi 6 (at least, that's what I've been told).
Anyway, to move the code in listing 1 from Windows (Delphi) to Linux (Kylix), I usually FTP it to my Linux machine, and then open the project in Kylix. I won't bother you here with details regarding .res, .opt, .cfg and .dfm files, we only have to worry about a single analias.dpr file here, which can be moved over and loaded in Kylix without too much trouble. Of course, loading in Kylix and recompiling with Kylix are two different matters. And since the original application is very BDE specific (TSession and TTable), we need to look at dbExpress alternatives instead (like SQLConnection and SQLTable).
But first, we need to replace the DBTables unit with SqlExpr. Now, we can replace the TSession with TSQLConnection. The AutoSessionName property makes no sense her, but we can set the ConnectionName to initialise the TSQLConnection component (and can make it active by setting Connected to true). Once we have a list of TableNames, we can again loop through it, and create TSQLTable components. The only difference with a BDE TTable is that we no longer need to mention a DatabaseName, but an SQLConnection instead (which must point to an existing SQLConnection instance, just like we should have used a TDatabase component in the BDE example, which should have been much better).

  program analias;
  {$APPTYPE CONSOLE}
  uses
    Classes, DB, SqlExpr;
  var
    i,j: Integer;
    TableNames: TStringList;
    SQLConnection1: TSQLConnection;
  begin
    TableNames := TStringList.Create;
    SQLConnection1 := TSQLConnection.Create(nil);
    with SQLConnection1 do
    begin
      LoadParamsOnConnect := True;
      ConnectionName := ParamStr(1);
      Connected := True;
      GetTableNames(TableNames);
    end;
    with TSQLTable.Create(nil) do
    try
      SQLConnection := SQLConnection1;
      for j:=0 to Pred(TableNames.Count) do
      begin
        writeln;
        TableName := TableNames[j];
        Open;
        writeln(TableNames[j],' ',RecordCount:4);
        for i:=1 to Length(TableNames[j])+5 do write('=');
        writeln;
        writeln('Field'#9'Name'#9'Type'#9'Req');
        for i:=0 to Pred(FieldCount) do
        begin
          write(i,#9);
          write(Fields[i].DisplayName,#9);
          write(FieldDefs[i].FieldClass.ClassName);
          if FieldDefs[i].DataType = ftString then
            write('[',FieldDefs[i].Size,']');
          if FieldDefs[i].Required then write(#9'Yes');
          writeln
        end;
        IndexDefs.Update;
        if IndexDefs.Count > 0 then
        begin
          writeln;
          writeln('Index'#9'Name'#9'Fields')
        end;
        for i:=0 to Pred(IndexDefs.Count) do
        begin
          write(i,#9);
          write(IndexDefs[i].DisplayName,#9);
          write(IndexDefs[i].Fields);
          writeln
        end;
        writeln;
        Close
      end
    finally
      Free;
      SQLConnection1.Free
    end
  end.