Virtual Tables and Cursor Adaptors

[tekhong]

Hello

May I know the difference between Virtual Tables and Cursor Adaptors?

Are they mutually exclusive meaning I have to decide between which one to use?

If it is the latter, then how do I decide?

Your advice is much appreciated

Thanks & Best Regards

[yvonne.milne]

Hi Tek Hong,

When you open a virtual table, you can access its underlying Cursor Adaptor and then the Cursor Adaptor properties and methods.

e.g.

open database southwind
use vcust
ca = cursoradaptor() // specify the alias if not currently selected
? ca.selectcmd

Regards,

Yvonne

[tekhong]

Hi Yvonne

Do you mean I can actually change the virtual table SQL on the fly?

Your advice is much appreciated

Thanks & Best Regards

[barrymavin]

Hi Tek Hong,

Yes.

ca.requery(" ... ")

[tekhong]

Hi Yvonne

Is there any documentation that explains the benefit of using cursor adaptor than normal SQL?

Alternatively, why not just use the table alias directly and the usual VFP data manipulation commands such as APPEND, REPLACE, DELETE?

Your advice is much appreciated

Thanks & Best Regards

[HankFay]

Hi Tek Hong,

Yes.

ca.requery(" ... ")

Hi Barry,

if the new sql adds fields or changes field order will this work in a) non-ui situations and b) where the VT is already showing in a UI component?

thanks,

Hank

[barrymavin]

ca.requery() replaces the WHERE clause and anything after it e.g. LIMIT or ORDER BY. The select list is in the VT definition.

If a section has a VT bound to it, a requery() will refresh it's contents. The cursor adaptor knows it has an associated section.