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Setting Options That Influence the Data Packets

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Go Up to Controlling What Information Is Included in Data Packets


The Options property of a dataset provider lets you specify when BLOBs or nested detail tables are sent, whether field display properties are included, what type of updates are allowed, and so on. The following table lists the possible values that can be included in Options.

Provider options :

Value Meaning

poAutoRefresh

The provider refreshes the client dataset with current record values whenever it applies updates.

poReadOnly

The client dataset can't apply updates to the provider.

poDisableEdits

Client datasets can't modify existing data values. If the user tries to edit a field, the client dataset raises exception. (This does not affect the client dataset's ability to insert or delete records).

poDisableInserts

Client datasets can't insert new records. If the user tries to insert a new record, the client dataset raises an exception. (This does not affect the client dataset's ability to delete records or modify existing data)

poDisableDeletes

Client datasets can't delete records. If the user tries to delete a record, the client dataset raises an exception. (This does not affect the client dataset's ability to insert or modify records)

poFetchBlobsOnDemand

BLOB field values are not included in data packets. Instead, client datasets must request these values on an as-needed basis. If the client dataset's FetchOnDemand property is True, it requests these values automatically. Otherwise, the application must call the client dataset's FetchBlobs method to retrieve BLOB data.

poFetchDetailsOnDemand

When the provider's dataset represents the master of a master/detail relationship, nested detail values are not included in data packets. Instead, client datasets request these on an as-needed basis. If the client dataset's FetchOnDemand property is True, it requests these values automatically. Otherwise, the application must call the client dataset's FetchDetails method to retrieve nested details.

poIncFieldProps

The data packet includes the following field properties (where applicable): Alignment, DisplayLabel, DisplayWidth, Visible, DisplayFormat, EditFormat, MaxValue, MinValue, Currency, EditMask, DisplayValues.

poCascadeDeletes

When the provider's dataset represents the master of a master/detail relationship, the server automatically deletes detail records when master records are deleted. To use this option, the database server must be set up to perform cascaded deletes as part of its referential integrity.

poCascadeUpdates

When the provider's dataset represents the master of a master/detail relationship, key values on detail tables are updated automatically when the corresponding values are changed in master records. To use this option, the database server must be set up to perform cascaded updates as part of its referential integrity.

poAllowMultiRecordUpdates

A single update can cause more than one record of the underlying database table to change. This can be the result of triggers, referential integrity, SQL statements on the source dataset, and so on. Note that if an error occurs, the event handlers provide access to the record that was updated, not the other records that change in consequence.

poNoReset

Client datasets can't specify that the provider should reposition the cursor on the first record before providing data.

poPropogateChanges

Changes made by the server to updated records as part of the update process are sent back to the client and merged into the client dataset.

poAllowCommandText

The client can override the associated dataset's SQL text or the name of the table or stored procedure it represents.

poRetainServerOrder

The client dataset should not re-sort the records in the dataset to enforce a default order.



See Also

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