Data Access and Transactions
Data Access and Transactions |
|
The first type of cursor is optimized for the most common type of database access—sequential, forward traversal of records. This is the default cursor type for Recordset objects created when you use the Execute method of the Command and Connection objects. Although you can still add, delete, and update records with a forward-only (but not read-only) cursor (depending on LockType), you cannot set a bookmark in the current row to return to the record later. If your cursor type supports bookmarks, you could save a bookmark to the current row if you need to come back later. Also, you cannot use the Resync method to view changes made externally to the Recordset.
Some providers (like SQL Server) implement the default forward-only, read-only cursor using a “firehose” mode, meaning that the connection is held open as long as there is data to retrieve. Once the cursor has been opened in this mode, the server does not wait for the client to request the next record and then provide it. Instead, the server sends the records as a continuous stream of data. Firehose cursoring is very fast, since overhead is only incurred as the data is read. Firehose cursors do not allow updates to the data.
See the following: