Supports

Your recordset can tell you what properties are supported by its OLE DB provider. Keep in mind though, that while the provider may support some functionality, a particular recordset might not. For example, you might have a recordset that presents a calculated field that does not correspond to an actual field in the database. While the provider may support updating for a recordset of your configuration, it will not be able to update that particular recordset.

The following table lists the options that you can query using the Supports method:

Attribute Name	Description	Option Constant
Add new	When Supports returns true, the provider allows for the AddNew method to be called for adding a new empty record to the recordset.	adAddNew
Approximate position	When true, the provider allows for the use of the AbsolutePage and AbsolutePosition properties.	adApproxPosition
Bookmarkable records	When true, the provider allows for the use of bookmarks in the recordset (a bokmark is a variant value returned from the Bookmark property, that uniquely identifies a record – bookmarks can be used to return to an exact location in a recordset).	adBookMark
Deletable records	When true, you may use the Delete method of a recordset to remove rows from the recordset.	adDelete
Find	When true, you can use the Find method to search a column in the recordset for a specific value.	adFind
Hold	When true, you can request more rows or move the row pointer without committing your edits.	adHoldRecords
Move back	When true, you can use MovePrevious, MoveFirst, GetRows and Move to move the record pointer backwards.	adMovePrevious
Resynchronize recordset	When true, the provider allows you to call the Resync method. The Resync method refreshes the recordset with any changes in the underlying data in the database, no new records are included in the Resync.	adResync
Updateable	When true, the provider will allow for changes to be made with the Update method of the recordset.	adUpdate
Batch updateable	When true, the underlying provider supports UpdateBatch and CancelBatch methods for the cursor type.	adUpdateBatch

The code sample below is a neat way of creating recordsets with different permutations of cursor types, lock types, and cursor locations, and finding out what each recordset supports based on those choices.

It's quite straightforward really. We'll use a simple HTML form to choose the lock type, cursor type and cursor position of the recordset, like this:

Hitting the View Support button will submit our form. After some unexciting variable declarations (which we'll skip here) we set the values for strLocation, strLock and strType – the variables that we'll use in a moment to open a recordset:

We'll set the SQL string, and open the connection to the pubs database, as we've seen before in this chapter. Then we can query the recordset against the database – using the strLocation, strLock and strType variables for the recordset's settings:

In this example, we're not interested in the results of the query – we're interested in what funtionality the recordset supports. So the rest of the page is given over to presenting the attributes, and whether-or-not they are supported by objRS: