Re: Using a Database within Windows + Dyalog APL

MS SQL Express 2005 is free for development (as is Express 2008), as
is IBM's DB2 Personal Edition, as is Oracle Personal; you just need to
sign up & download.

During development, you have several pathways, especially with Dyalog:

1. Use their ODBC wrapper ... SQL Link. This ties you down to your
data later being entwined with your application code and ODBC is
legacy software although quite prevalent.

2. Use ADO 2.8 with ODBC drivers (same comments as in 1 applies) or
with Providers. ADO too is legacy software although likely to be
around for a long time.

3. Use the ADO.NET base classes with APL/W. You can use the native
clients that Microsoft & Oracle supply for their respective
databases ... these are dedicated drivers (ratther than ODBC or
Providers which are somewhat generic). Your data layer code will still
be entwined with your application code.

My preferred approach would be as follows:

1. Write a COM component using C# (also possible with VB6.0). I guess
you can emulate this with a namespace.

2. The COM should allow clients to choose for alternative databases
i.e SQL Express or Oracle or DB2 etc.

3. Keep the COM simple & robust and secure.

a. The COM should take a property - which provider's database to use.
b. It should provide a method, say ExecuteQuery, that returns a
recordset i.e. DQL.
c. It should provide a method, say, ExecuteNonQuery that does not
return a recordset i.e DML etc.
d. Connect to the database using a UID & PWN stores in the Registry,
encrypted.
e. User logins should be managed by your application code-details can
be stored in a table in the database.

Beyond development, you need to comply with each vendors EULA terms.
For SQL Express, I believe you just need to get Microsoft's approval
(for free).

I would certaily NOT emulate/build a database in APL, if only because
APL does not provide intrinsic means of managing data types that
databases do.